基础语法
二、主语和主语补语的一致
主语和主语补语的一致主要表现在数的方面。在大多数情况下，主语和主语补语在数的方面应该是一致的：
Both Jimmy and Jackson are graduate students.
The deer is a shy（怕人的，易受惊的）animal.
但有时，主语和主语补语的数也会不一致，表现在以下两种情况：
1 主语为复数而主语补语则为单数形式。
在这种句子中，主语补语采取单数形式是为了表示一个整体概念，有时候某些单数形式的主语补语在意义上相当于形容词：
Tomatoes are a vegetable.［表示整体概念］
Evening classes are a constructive idea.［同上］
My wife and children are my sole care.［同上］
Your letters are always a delight. (a delight=delightful)
Good manners are a rarity among young people nowaday.［a rarity=rare极少见的］
2 主语为单数而主语补语却为复数形式。
这时，主要取决于句意：
My principal anxiety is my aged parents.
The cargo is potatoes.
The chief trouble here in summer is mosquitoes that swarm about you in the evening.
The room is magazines and pens. 这房间里到处都是杂志和笔。
Jack is pals with Mary. 杰克和玛丽是朋友。
在下列固定词组中，主语和主语补语在数上不一致，但符合英语习惯用法：
Two soldiers stand（或mount）guard（站岗）at the entrance.［在stand/mount guard习语中，guard总是用单数，无冠词］
Two birds fell (a) prey to the cats（为猫所食）.
Two of the campers stood sentinel（守卫）while the others slept.［stand sentinel也是习惯用语，sentinel用单数，无冠词］
He/They turned traitor under the enemys severe torture. 在敌人的严刑拷打下，他/他们成了叛徒。［turn traitor是习惯用语，不管主语是单数还是复数，主语补语traitor总是用单数，无冠词。如把此句中的turned改为became，则应说：He became a traitor...或They became traitors...］
再如：
Women have eyes for fashion. 女人对时装很感兴趣。
Tom made faces at her. 汤姆向她做鬼脸。
Many fall victim. 许多人都成了受害者。［不用victims］
They are always the victor. 他们总是赢家。［不用victors］
He is shipmates with you. 他和你同乘一条船。
I am quits with you. 我们两清了。
三、代词的一致
代词一致是指句中代词应与它所照应的名词词组在数、性、人称等方面彼此保持一致。
Robert and Henry havent made up their minds yet.
I bought a fridge. It is of American make.
I have two fridges. They are both of American make.
▶▶ 当everyone，everybody，no one，nobody，anyone，anybody，someone，somebody用作主语时，其相应的代词在标准化考试中按语法一致的原则采取单数形式。
Everyone had his say at the meeting. 大家都在会上发了言。
Everybody looks after himself.
No one has yet availed himself of this offer.
Anyone who fails (=fails in) the driving test will not be able to get his license.
例 Everyone in the audience kept_____eyes focused on the curtain behind which Layton had taken refuge.
A. his
B. their
C. its
D. her
［答案：A］
但在现代日常用语中，因everyone，everybody，anyone，anybody统指男女两性，已改用复数代词，听起来更合理，更合英语表达习惯。在当今的英语考试中也采用复数形式，诸如英国的《COBUILD等英汉双解词典》已采用这一复数代词的指代法。例如：
Everybody knows what they have to do.
If anybody calls while Im out shopping, tell them to call back this evening.
▶▶ everything，anything，something，nothing等不定代词作主语时，句中相应的代词一概用单数形式。
Everything is ready, isnt it?
Something strange happened yesterday, didnt it?
▶▶ 当代词所指的对象为并列结构时，代词的单复数应按并列结构的意义来决定。
The old woman and her daughter managed to support themselves by being babysitters.［老妇人和女儿是两人，故代词用themselves］
The owner and the captain refused to abandon their sinking ship.［船主和船长是两个人，故代词所有格用their］
The owner and captain refused to abandon his sinking ship.［船主兼船长是指一个人，故代词所有格用his］
I bought bread and butter at the supermarket, and they cost four dollars.［面包和黄油，这里指两件东西，故代词用they］
I like bread and butter, and this is my favorite food for breakfast.［这里指涂有黄油的面包，是一种东西，故代词用this］
最后需要加以说明的是，一致性的处理在正式文体及非正式文体中往往不一致；这种情况在实际应用中是一个很普遍的现象。譬如说本章中曾讲到由连词or，either...or...，neither...nor...等连接的并列主语，通常根据就近原则，要求谓语动词与最靠近的并列主语保持数的一致，也就是说，最靠近的主语是单数时动词也用单数，最靠近的主语是复数时动词也用复数。本章节曾列举五组实例相互比较从而说明这一根据就近原则在数方面的一致性用法。但日常的非正式文体中由or，either...or...，neither...nor...等连接的并列主语也可根据意义一致的原则采用复数形式的动词。如：
Reward or punishment are［正式文体用is］meted out quite independent of human interference.
If either Arther or Lucy come［正式文体用comes］, they［正式文体用he or she］will want a cold drink.
Neither she nor her husband have［正式文体用has］any idea of it.
鉴于国内外标准化考试中的结构部分均以正式文体为准则，作者着重按正式文体的要求来处理一致性这一语言现象。
四、并列（又称平行排比）结构中成分宜保持一致性
在日常英语写作中，长句、复合句、三项排比、非谓语等的运用比比皆是，这时就要求作者在语法结构等方面做到前后对应，保持一致，以此使句子保持平衡和协调。此技巧掌握得好，定能使自己写出的句子对仗工整、气势磅礴。
The students task is reading English, speaking English and listening to English. 学生的任务就是读英语，说英语，听英语。
Comment is often made about activities which are relatively easy and satisfying, like arranging flowers; but not about jobs which are hard and dirty, like scrubbing floors.［两个about都是修饰comment］那些相对轻松和讨好的活儿，例如插花，就更容易获得人们的评论；但是像擦地板这样又苦又脏的工作却不予置评。
The instrument has been welcomed by users because of its stability in serviceability, reliability in operation and simplicity in maintenance. 该仪器性能稳定，操作可靠，维修方便，因而受到用户欢迎。
另外，结构成分的一致除了并列结构外，还有比较结构、排比结构等。
Exercises
一、多项选择
1. The data_____arrived just in time.
A. has
B. have
C. have been
D. has been
2. George is one of the brightest students who_____from New York University.
A. is graduated
B. has graduated
C. have graduated
D. had graduated
3. Almost immediately_____flashed on the Internet and was picked up, half a world away, by John Hofsess, executive director of the Right to Die Society of Canada.
A. a word
B. words
C. the word
D. word
4. The team_____preparing for its big game.
A. were
B. are
C. have been
D. is
5. I want to have two_____.
A. scissors
B. sets of scissors
C. pieces of scissors
D. pairs of scissors
6. Anybody_____knows anything know this.
A. who
B. not
C. doesnt
D. that
7. Each bus and tram_____with colored lights.
A. is decorated
B. are decorated
C. decorates
D. decorated
8. Nebraska has floods in some years, _____.
A. in others drought
B. droughts are others
C. while other droughts
D. others in drought
9. Commercial expansion from city to suburb has affected the way people in the United States_____.
A. living and working
B. they live and work
C. live and work
D. to live and to work
10. Before linoleum was invented in 1860, _____hard-wearing, easy-to-clean flooring.
A. any house did not have
B. no house have
C. no house had any
D. any house had not
11. Tom is so poor that even five dollars_____a big sum to him.
A. is
B. are
C. add
D. equal
12. Part of the books_____arrived.
A. is
B. have
C. was
D. has
13. The office staff_____gathered to hear the President speak.
A. is
B. are
C. be
D. will
14. The wheel and axle_____a rotating lever.
A. is
B. was
C. are
D. were
15. No sulfur and no phosphorus（磷）_____present in this product.
A. are
B. were
C. will
D. is
二、用is/are，was/were，has/have或does/do填空
1. Nothing but two empty bottles_____been found in the victims bedroom.
2. A large number of cattle_____slaughtered for meat every day.
3. Industry, not ability, _____the key to success.
4. One-third of the guests_____left.
5. One-third of the land_____cultivatable.
6. Stealing cars_____a common crime nowadays.
7. Our football team_____won the match.
8. The enemy_____been driven out of the country.
9. A vase filled with camellias_____placed on the table.
10. There_____lots of useful information in this article.
11. Three times one_____three.
12. What worries the people there_____disease and famine.
13. There_____a pan, a pencil and two dictionaries on the desk.
14. The number of cars in Tokyo_____increasing every year.
15. A black and white kitten_____found in the garden yesterday.
16. They say riches_____wings.（人们说财富易散。）
17. Collecting stamps_____my favorite hobby when I was a boy.
18. The long and the short of the matter_____that they both incurred heavy losses.
19. A summons_____been sent to the witness.
20. There_____one or two apples left in the basket.
Keys
一、多项选择
1.［B］data是datum（材料）的复数形式，故用have。
2.［C］题句中关系代词who不指one，而是指复数名词students，“graduated（或be graduated)from＋校名”表示“毕业于……学校”。题句中未提供明确时间，一般宜用现在完成体，故选C。A项中之is改are便可。
3.［D］word用作单数时前不用冠词，作“news；information”解，如：Finally word came that they had arrived there safely.（最后传来了他们已安全到达那里的消息。）本题意指“消息马上出现在计算机国际互联网上并被北半球加拿大安乐死权利协会执行主席John Hofsess所检索。”
4.［D］题句中出现的its指team；显然，集体名词team这里表示整体，不是表示team中的各个成员，故选D。题中之game指成为打猎目标的野生鸟兽，系不可数名词。如要表示“一头猎物”，该用a head of game。
5.［D］two pairs of scissors两把剪刀，合句意。
6.［A］在everybody，everyone，anybody，anyone，somebody，someone等词后面宜用who（用作从句中主语），whom（用作从句中宾语），不用that。如When I entered, they were talking about somebody whom I didnt know.（whom作know的宾语）/Is there anyone here who knows Spanish?（who作know之主语）
7.［A］Each bus and tram或Each bus and each tram都接单数动词，every用法和each相同。
8.［A］in others=in other years。题句意指“在有些年份Nebraska发生水灾，在有些年份则发生旱灾。”其余皆不合语法。题中之drought也可用作不可数名词，如areas of Africa affected by drought（遭受旱灾的一些非洲地区）。
9.［C］the way people in the United States live and work=the way in which（或the way that）people in the United States live and work。
10.［C］题句的主句缺主谓，故选C。A项在语法上尚可，但不合英语的习惯表达法，在带有no，nothing，any，anything的句子里，按习惯用法应采用“主语否定，谓语肯定”这一结构形式来表示否定的意思。如“这项工作一个人是干不了的。”在英语中不能说“Anybody cannot do the job alone.”应说“Nobody can do the job alone.”因此，A项不妥。linoleum：油地毡。
11.［A］five dollars作“整体”概念考虑。
12.［B］Part of...=A part of...；Part of接复数名词时便采用复数动词，接单数名词时则采用单数动词。
13.［B］staff作“全体工作人员”解，谓语动词用复数。
14.［A］在机械学中wheel和axle指“轮轴”，系整体，故接单数动词is。
15.［D］
二、用is/are，was/were，has/have或does/do填空
1. has。主语nothing是单数。
2. are。cattle指牛的总称，接复数动词。表示“一头牛”时用a herd of cattle，表示“30头牛”时用thirty head of cattle，head不能用复数。
3. is。industry在这里的意思是“勤奋”。
4. have。组合数词后面的介词接复数名词时，便采用复数动词，接单数名词便采用单数动词。如：One-third of the money is hers.
5. is。（同上）。
6. is。因主语是动名词短语。
7. has。team这里指足球队表示整体。
8. have。the enemy用作集体名词时指敌军，单复数动词都可接，但复数动词更为常见。
9. is。
10. is。lots of系修饰词，主语系单数名词information。
11. is。
12. is。这句结构也可在数上略为变动，改为what worry（复数动词）the people there are（复数动词）disease and famine。
13. is/are。按包括TOEFL在内的传统英语的要求，应用are，但现代英语和当前标准化考试都倾向用is，因第一个主语pen前有a。
14. is。the number of接复数名词，但采用单数动词。a number of接复数名词和复数动词。
15. was。a black and white kitten指一只黑白间色的猫，a black and a white kitten则指两只小猫，一只黑、一只白。
16. have。
17. was。
18. is。The long and (the) short of the matter（第二个the也可省略）意指“这件事情的要点或主要意思”，后接单数动词。
19. has。summons是复数形式的单数名词，作“传票”解，后接单数动词。
20. are。主语apples是复数。
第六章 动词
一、不规则动词
英语动词有规则动词和不规则动词之分。规则动词的过去式和过去分词形式相同，如walk（散步），walked，walked。但不规则动词的这两种形式却往往不相同，如bite（咬），bit，bitten。然而也有一些不规则动词，它们的过去式和过去分词同它们的原形一样，如hit（打击），hit，hit。
英语的不规则动词，虽然看来是个简单的语言现象，却不可掉以轻心，因它们同英语的时态、语态、分词和合成词都有密切关系，可说是基础的基础。故标准化考试常考这一语言现象。
例 Pickling（腌渍）of foods (A) begun (B) in prehistoric (C) times (D).
［分析］B孤零零地用了过去分词形式，显然是错的。句子表达的是过去的意思，谓语动词应用过去式began。
例 Tons (A) of boulders were leaved (B) scattered by glaciers all over (C) what was to become the New England landscape (D).
［分析］leave系不规则动词，它的过去式和过去分词均为left，故应把B改为left，与前面的动词were构成过去时被动语态。
二、特殊连系动词
除了系动词be即am，is，are，was，were之外，还有其他一些动词，它们后面不是跟副词而是跟形容词或名词作为表语。在语法结构上，这些动词因所起的作用和系动词be一样，故称特殊连系动词。例如，英美人不说“The air has suddenly grown coldly.”而是说“The air has suddenly grown cold.”因grow有时用作特殊连系动词。
例 It is prohibited by law to mail through parcel post any merchandise that might prove_____in transport.
A. dangerous
B. with danger
C. dangerously
D. to the danger
［分析］在上题的定语从句中动词prove系特殊连系动词，后面不能跟副词来修饰，须接形容词作为其主语that的表语，故应选A。
1. 特殊连系动词的分类
1 表示一个特征或状态。
这类动词有feel，look，sound，taste，smell，appear等：
His argument does not sound very reasonable.
The perfume smells nice.
These apples look ripe.
The milk tastes sour.
The sun feels good. 阳光宜人。
The verdict appears just. 判决看来很公正。
2 表示由一种状态进入或转变为另一种状态。
这类动词有become, grow, get, turn, fall, go, come, run等：
Our technique is becoming increasingly specialized. 我们的技术正在变得越来越专业化。
Stop it; he is getting drunk. 别再这样搞了，他快喝醉啦。
The engine runs hot. 引擎发烫了。
I regret that my question goes unanswered. 很遗憾，我的问题未得到答复。
He turned nasty when he found he had been ripped off. 他发现被人“斩”后大为光火。
His mouth fell open（变得张口结舌）when the police questioned him.
You will grow used to the life style here in course of time. 日子久了你会习惯这里的生活方式的。
Your shoelaces have come undone. 你的鞋带散了。
3 表示保持某种状态。
这类动词有continue, keep, remain, prove, turn out, stay, sit, lie, stand等：
He eats much but remains thin. 他吃得很多，可依旧很瘦。
The stock market continued bullish for as long as two years. 股市继续保持牛市行情达两年之久。
We can keep abreast of what is going on by reading the newspaper. 通过读报我们便能跟上形势发展。［注意：abreast这里是形容词］
The boy will turn out (to be) a marvellous man. 那男孩将成为一个了不起的人。
She stayed (=remained) single all her life.
The new method proved efficient.
Monica sat motionless, waiting for the interview.
Gilbert is still lying（lie之现在分词）awake.
I stand innocent of any wrong. 我未做错任何事。
2. 特殊连系动词的固定搭配
blush crimson/red 羞得脸通红
The girl blushed crimson when her boyfriend kissed her in the presence of his friends（当着他朋友的面）.
break free/loose 挣脱；迸发
In the sweeping economic reform, peoples creativity is breaking loose. 在势不可挡的经济改革中，人们的创造性正在迸发出来。
come easy 变得容易
Skill comes easy through constant practice. 技艺熟能生巧。
come loose/undone 松掉
Some of the pages have come loose. 有几张书页松脱了。
come right 没问题
Dont worry. Everything will come right in the end. 船到桥头自会直。
come true（预言、期望、梦想等）实现；成为事实
I wonder whether the prophecy（预言）will come true.
cut loose 摆脱
The boy left home and cut loose from his parents control. 该男孩离开了家，摆脱了父母的控制。
fall asleep 入睡
The child fell asleep just now. 这孩子刚睡着。
fall due 到期
The rent falls（或comes）due tomorrow; dont forget to pay it.
fall flat 完全失败；达不到预期效果
The project fell flat. 该项目完全失败了。
The speakers joke fell flat on the audience. 讲话人的笑话没有能使听众感到好笑。
fall short 未中标；达不到标准或要求
The arrow fell short of the target. 箭未射中目标。
Supply falls short of demand. 供不应求。
go bald（头发）变秃
I started to go bald at about 40. 我40岁左右开始秃顶。
go bad（食物等）变质
Food goes bad easily in summer.
go crazy/mad 发疯；着迷
Mike has gone crazy (mad); there is no doubt about it. 迈克发疯了，这是毫无疑问的。
The girls all went crazy (mad) over the film star. 姑娘们都为该电影明星神魂颠倒。
go dead（电话）中断；（电池）电用完
The telephone suddenly went dead in the middle of our talk.
go easy 省着点吃……；放（某人）一码（后接介词on）
There is not much cocoa left; lets go easy on it. 可可粉不多了，咱们省着点喝吧。
As you are a teenager, well go easy on you. 因你是个十几岁的孩子，我们就放你一码算啦。
go sour（牛奶等）变酸
I forgot to put the milk back in the fridge; it has gone sour.
go white（脸色，头发）发白
My father went white（头发变白）at the age of 40.
go wrong 走入歧途；弄错；不如意
People help teenage boys and girls who have gone wrong. 人们帮助失足的男女青少年。
You cant go wrong in buying this bargain. 买这个便宜货你错不了。
Something went wrong today. 今天事事不称心。
lie awake 躺着醒着
He has not gone to sleep yet（尚未睡着）; he is still lying awake.
lie waste（土地）未被开垦
Large areas lie waste for lack of manpower. 由于缺少人力，大片空地未得到开垦。
rest easy 放心
You can rest easy. 你们尽可放心。
rest assured（指对……）放心（后接of)
You can rest assured of our best cooperation. 你们请放心，我们会给予最佳合作。
rest content 对……很满意（后接with）
I rest content with my life at present. 我对目前的生活心满意足。
ring false 听起来不真实；听声音像假货［反义词组为ring true］
Their statement rang false. 他们的陈述听起来不真实。
These coins ring false. 这些钱币听声音像是假货。
ring hollow 听上去空泛泛
The promises made by that friend of yours ring hollow. 你那位朋友所许下的种种诺言听上去都是泛泛空话。
run dry 干涸
The well has run dry. 这井已干涸。
run mad=go mad
run hot 发烫
The engine is running hot. 引擎在发烫了。
run rampant（植物）蔓生；（谣言等）四处传开
The rich soil has made the plants run rampant. 肥沃的土壤使植物十分繁茂。
Gossip has run rampant. 流言已四处传开。
run wild 变得荒芜；失去控制或约束；
The garden has run wild. 花园荒芜了。
Ivy ran wild all over that old house. 常青藤爬满那幢旧房子。
Dont let your children run wild. 别把孩子宠得毫无管束。
wear smooth 磨得光滑
Constant treading has worn the cobbled street smooth. 人们经常踩踏，已把这条石子路磨得很光滑。
wear thin 磨薄，穿/用薄；慢慢失去；失去吸引力
The soles of these shoes have worn very thin. 这双鞋底已穿得非常薄了。
My patience began to wear thin during the long wait. 在长时间的等待中我渐渐变得不耐烦了。
A joke heard too often can wear thin. 笑话重复太多便会失去吸引力。
wear hollow 使耗成空壳
This tooth of yours is almost worn hollow. 你这颗牙几乎给蛀空了。
3. 特殊连系动词与实义动词
有些特殊连系动词也可用作一般实义动词；这样用时含义有所不同，它们应和副词一起用，而且不能再接形容词。试比较：
The accident appeared impossible. 这个意外事件看来似乎是不可能的。
Betty suddenly appeared in the doorway. 贝蒂突然出现在门口。
Anthony looks angry. 安东尼看来在发火。
Anthony is looking at you angrily. 安东尼在发怒地看着你。
The soup tastes wonderful. 这汤尝起来味道极佳。
I tasted the soup suspiciously. 我怀疑地尝一尝这汤。
My skin feels rough. 我的皮肤摸起来很粗糙。
The doctor felt my arm carefully. 医生很当心地摸弄着我手臂。
在上面四组例句中，每组第一句中的动词系特殊连系动词，后跟形容词；在第二句中该动词用作一般实义动词，意义也有所改变，故为副词所修饰。
4. 表层结构和深层结构在特殊连系动词结构中的应用
有时，一个非及物动词后面不跟副词而是接形容词或名词，例如：
The day dawned misty.［动词dawned后面接形容词misty，不跟副词mistily］
Eloise left a child, and came back a mother of three children.［动词left和动词词组came back后面均跟名词］
从表层结构看，上列两个例句中似乎都有问题，第一例句中的misty应改为mistily，第二例中的不及物动词left和不及物动词词组came back后面都跟名词令人费解。但当我们对上列两个例句的表层结构深入下去后，便可发现它们的深层结构：
The day dawned. It was misty.
Eloise left. She was a child. She came back. She was a mother of three Children.
在上列两个深层结构中，代词it指the day，即两个主语相同，it后面又有系动词was;在符合这两个条件的情况下，两句便可合并形成表层结构：The day dawned misty.在这一表层结构中，动词dawned的性质已由一般动词变为半系动词（semi-link verb）。同样地，在上面第二个深层结构中三个代词she指的都是Eloise，四个主语指的是同一个人，第2和第4句中又都有系动词was，故合并成这一表层结构：Eloise left a child and came back a mother of three children. 当然，动词left和动词词组came back在这一表层结构中也都变为半系动词。这种带有半系动词的表层结构有时也应用在写作中，如：
Robert went home disappointed［不用disappointedly，因深层结构为Robert went home. He was disappointed.］
Geoffrey and Gerald parted the best of friends.［此句的深层结构为Geoffrey and Gerald parted. They were the best of friends. 第二句中的They指代Geoffrey和Gerald，后面有系动词were，故可合并成表层结构。］
再如：
The man jumped into the water to save the drowning boy. He was fully clothed.便可合并成表层结构：The man jumped fully clothed into the water to save the drowning boy. 那男子没有脱衣服就跳进水里去救那溺水的男孩。
唐朝诗人贺知章的名诗《回乡偶书》中的第一句“少小离家老大回”的英译就可采用这一由深层结构演化而来的表层结构：
或
I left home young and came back old.
I left home a child and returned an old man.
下面是一例测试表层结构的标准化考题，难度极大，90%以上的考生都失分：
例 Mrs. Robinoson stared at (A) the robber, and then (B) crumpled to (C) the floor unconsciously (D).
［分析］因题中第二部分系深层结构，后面省去两个she，即and then she crumpled to the floor; she was unconscious.第二个she后面有was，故可合并表层结构she crumpled to the floor unconscious.故(D) unconsciously，错，改为unconscious。
中国人传诵着一句名言“莲出污泥而不染”来形容一个品格高的人处于逆境中而能洁身自好。这句名言汉译英时宜用表层结构。为便于读者掌握，现分两步处理：
第一步：Lotuses emerge from the filth. They are unstained.
第二步：They指代lotuses（两个主语相同），后面出现系动词are，两步便可合并为一步，成为表层结构，即：
Lotuses emerge unstained from the filth.
三、情态动词
1. can (could)和be able to用法上的区别
1 can可以表示能力，指某人具有某种知识和技能而能够做到某事。can用于指现在，过去时则用could。
Can you speak English? 你能说英语吗？
He said that he could do anything we wished. 他说他能做我们想要他做的任何事情。
但当表示经过艰苦努力而成功地做到或设法做到某事时要用be able to，而不用can。试比较下面两例：
He couldnt drain the whole bottle of beer. 暗示他没能力把整整一瓶啤酒一饮而尽，结果也未尝试着去喝。
He was not able to drain the whole bottle of beer. 隐含他尝试着去喝，但结果没能一口气喝完。
2 can表示现在时，无人称和数的变化。be able to则不同，有人称和数的变化，并可用于各种时态。
在表示意愿或准许的含义时或在表示将来时的 if 从句或when从句中can也可表示将来，这一用法并不多见。
Can you translate this poem?［表现在］
Can you come to our party?［表意愿，相等于 will，指将来］
If you can help me with the work, I will buy you a gift. 你如能帮我干这工作，我定会买件礼物送你。［用在if从句中表将来时］
As you look so listless, you can take this afternoon off. 你看来精神很不济，今天下午你就休息吧。［指将来，表准许］
On graduation from college, I shall be able to fend for myself. 大学毕业后，我将能自力更生了。［表将来，这里不能用can。fend for oneself自谋生计］
注：① 表示“准许”时，can可表示现在：We cant wear jeans at work. 我们上班时不准穿牛仔裤。be able to 则不能用来表示准许或许可，如: She said that I could（不能用I was able to）take any one of her books I wanted. 她说我可以拿她所有书中我要的任何一本书。
② 表示准许或许可时，通常用can，不用could。
A: Could I use your bike for a while?［这里could表请求之意］
B: Yes, of course you can.［不用could，表许可］
The girl is too timid. She has not been able to get a licence so far. 这姑娘太胆怯，她至今还未能拿到驾驶证。［表现在完成时］
He told me that since the traffic accident, he had not been able to walk properly. 他告诉我，自那次交通事故后他一直未能正常行走。［表过去完成时］
3 could和was/were able to用法上的区别。
A. 表示时间跨度较大、笼统的过去时段中具备的能力时 could和was (were) able to 可换用。
He could (was able to) swim across the Huangpu River when he was a kid. 他还是小孩子时就已能游过黄浦江了。
She was able to (could) sing like an angel when she was young. 她年轻时歌唱得能像天使般那样动听。
B. 表示完成过去某一具体动作时，只能用was (were) able to，不能用could。
After six hours climbing, we were able to reach the top of the mountain. 爬了6小时后，我们终于登上了山顶。［指过去某一次具体的爬山活动］
He was a terrific liar；he could (was able to) make anybody believe him. 他是个说谎大王，能使任何人相信他的谎话。［这里anybody表示一个笼统的泛指概念，故could或was able都可用］
When I was younger, I was not able to (couldnt) decide what I wanted to do. 我年轻时拿不定主意自己要干什么事。［在否定结构中 could和was(were) able to两者都可用，无差别］
例 He could (A) climb to (B) the top of the (C) mountain in spite of (D) the snow.
［分析］上题题意是“尽管山上积雪，他还是爬上了山顶。”表示完成过去某一具体动作时，只能用was(were) able to，故A项错，把could改为was able to。
从上面试题，可看出was (were) able to表示过去做成某具体事情的能力时，相等于 managed to do sth.或succeeded in doing sth.。由此可见，当表示“经过多年坚持不懈的努力，她终于赢得了大奖”时，便可说“After years of persistent efforts, she was able to win the grand prix.”［grand prix是“大奖”；“大满贯”则叫 the grand slam］
4 can和could的一些其他用法。
两词各种功能基本相同。除了could是can的过去式外，could比can更婉转、客气。
A. 表示可能性（指可以或了解做某事）。
表示可能性时常用于疑问句和否定句，但有时也用于肯定句和进行时。如：
The story is sensational; it cant be (couldnt be) true, I think. 这报道耸人听闻。我想这不可能是真的。［否定句］
He was living in Moscow when I last met him about five years ago. Can (could) he still be living there? 我上次约五年前碰到他时他正住在莫斯科。他可能还住在那里吗？［疑问句，进行时态］
We can (could) dine out tonight. 我们今晚可以在外面吃。［肯定句］
B. 表示婉转的命令或批评。
You can (could) go and buy a packet of cigarettes. 你去买包香烟来。
You can (could) tidy up your room, Mike. 迈克，整理整理你的房间吧。
You can (could) be more careful at your work. 你工作要更细心些。
C. 表示偶尔会出现的一种反常态的表现。
It can (could) be very cold in May here. 这里五月份有时会非常冷。
Sometimes our manager can be very tactless in dealing with interpersonal relations. 有时我们的经理在处理人际关系上会很不讲究方式。
Man can (could) be more cruel than wild beasts. 人有时会比野兽更残忍。
D. 用于修辞性问句。
修辞性问句以修辞手段表意而不需回答，借此表示某种情绪，如：Is that a reason for complaint? 难道那就是抱怨的理由吗？can也用于日常的修辞性问句中，如：
He is never content with his lot.What on earth can satisfy him? 他从不知足。究竟什么能满足他呢？［表不满情绪］
Time is so pressing. How can I complete such a task single-handed? 时间这么紧，我独自一人如何完成这样的任务呢？［表难以办到的畏难情绪］
以上两例表示较为强烈的不满及畏难情绪，can要比could更适宜些。
E.“can（或could) have+过去分词”表示过去可能发生的事；“cannot（或could not）have+过去分词”表示过去不可能发生的事。
The car and the van collided head-on in thick fog.Both drivers can (could) have been seriously hurt in the accident. 那辆小轿车和货车在浓雾中迎面相撞，两位驾驶员可能在那次交通事故中受了重伤。
My electronic calculator has disappeared.Who can（或could）have picked it up on the sly? 我的电子计算器不见了，谁会顺手牵羊把它拿走呢？
He started early. He cant (couldnt) have missed the train. 他动身很早，不可能误车的。
注：① can (could) have+过去分词也可用于完成进行时，即can (could) have been+现在分词，否定式也一样。如：
They can (could) have been discussing the problem yesterday afternoon. 他们可能昨天下午一直在讨论这问题。［肯定式］
They had two math classes yesterday morning, so they couldnt/cant have been playing table tennis all yesterday morning. 他们昨天早晨有两节数学课，因此不可能整个上午都在打乒乓球。［否定式］
② could have+过去分词表示原本可能的动作。
You could have finished your thesis last week. 你原本可以在上星期完成你的论文的。
You could have passed the driving test, but you were too nervous. 你原本可以通过驾照考试的，但你太紧张了。
2. may和might
1 may表示“许可”，“可以”，用于陈述句、疑问句和否定句，它的过去式是might。
表“许可”时may和might要比can和could更正式，might和could则比may和can更婉转、更有礼貌。如：
You may have some smoke here.［陈述句］
Students may not refer to books in the examination room. 学生在考场中不准参考书本。［否定句］
Visitors may not walk on the grass in the garden. 参观者不准在花园的草地上行走。［否定句］
A: May I come around in the morning? 我上午来好吗？［疑问句］
B: Yes, please do. 行，好的。
注：表肯定回答时，可用“yes, please do”或“yes, you may”（通常不用You might）。
2 回答问题表示“不许可”时可用cant或may not。
—Can I be excused from the meeting? 我可以不参加这个会吗？
—No, you cant. 不，不行。
—May I use your dictionary for about two hours? 你的字典我可以用两小时左右吗？
—No, you may not. 不，不行。
3 may not也可表示“不许可”，表示该意思时，它的过去形式不是might not。试比较：
Ike may not go home right after school. He will have to finish yesterdays homework. 埃克不准一放学马上回家，他得补做昨天的作业。
Ike might not go home right after school. He will participate in the school orchestra rehearsal. 埃克可能一放学不会马上回家，他要参加学校管弦乐队的排练。
▶▶ might not作为may not的过去式只能表示“不可能”，不能表示“不准，不许可”，故上面第1例“Ike may not go home right after school. He will have to finish yesterdays homework.”只能表示“不准，不许可”的意思。但语气要比“He is not allowed (permitted) to go home right after school”婉转得多。
4 may 表示的“可能”，比might表示的可能性较小，或者表示更委婉的语气。
They may not leave so early. 他们可能不会这么早离开。［否定句］
One may live a hundred years, but cannot live to three hundred years. 人可能活到100岁，但不可能活到300岁。
区别下面两个句子：
两句都表示可能借给你那本小说，但第二句的可能性要比第一句小。
Tom may lend you the novel.
Tom might lend you the novel.
注：can与may表示“可能”时要注意以下几点：
① 在疑问中表示“可能”时，按标准用法须用can不宜用may。如：
A: Where can she be? 她可能会在哪里呢？［疑问句不用may］
B: She may be at the nearby cybercafe wading through some websites. 她可能在附近的网吧，游览几个网站。［陈述语，可用may］
② 在口语中发may not 时，如果重音落在not上意思便由“不可能”转为“不准许”，如：
The naughty boy may not leave after school. 这个顽皮的男孩放学后不准回家。［重音落在not上］
在书面语言中may not可能会引起歧义，故表示“不可能”宜用cant。
③ 在肯定陈述句中，may和can都能表示“可能”（probability），但在含义上有微细的差别。比较下面两例：
Even on Saturdays and Sundays, this busy road can be blocked. 即使逢星期六及星期日，这条繁忙的道路也可能会堵。［指逻辑推理上的可能性］
Even on Saturdays and Sundays, this busy road may be blocked. 即使逢星期六及星期日，这条繁忙的道路也要堵。［指事实上的可能性］
④ may表示“可能”时一般不用于疑问句，而以其他词语来替代。
如：May he capture the intercollegiate table tennis championship for 2007? 他有可能夺得2007年大学校际乒乓球联赛冠军吗？
上列是个疑问句，may 表“可能”不妥，可改为Can he capture...?或Is he likely to capture...?或Is it possible for him to capture...?
5 may/might have+过去分词表示对过去发生事情的一种猜测，might比may在语气上更婉转。
He did not leave till as late as two oclock.He may/might have missed the train. 他挨到2点钟这么晚才动身，他很有可能已误车了。
You may/might have read that very stirring news report yesterday. 你昨天可能已看了那份非常激动人心的新闻报道。
The two may/might not have met that night. 这两个昨晚可能没有见面。
注：上一结构还可用来表示“本来可能发生但却没有发生”或“本来可能完成但却没有完成的事情”。这样用时，一般都用might或could而不用may或can。如：
You were marvellously lucky to have a narrow escape from that accident. You might have got killed. 那桩事故中你九死一生，算你命大；你本来可能会送命的。［表一桩“本来可能发生但却没有发生的事情”］
You might have/could have passed the examination, but you did not work hard enough. 你本可以通过这次考试的，但不够努力。［表本来可能完成或做到但却没有完成或做到。］
6 表示委婉的责备时只能用might，用于一般现在式或完成体。
You might ask me before you use my computer. 你可先问问我再用我的电脑嘛。［表现在］
You might have lent her a helping hand at that time. 那时你蛮可以拉她一把的嘛。［表过去，原可做到但却没有做到］
7 表示祝愿时只能用may。
A. may用于句首，主谓倒置。
May you succeed! 祝你成功！
May you live long! 祝你长寿！
May your birthday be happy! 祝你生日快乐！
B. 副词或形容词置于may之前，主谓也须倒置。
Long may you live! 祝你长寿！［副词long置于句首］
Happy may your birthday be! 祝你生日快乐！［形容词位于句首］
注：may还可用于对死者的祝愿，如May he rest in peace! 愿死者安息吧！
8 may/might的句型结构。
A. may well接动词原形，作“理应，有充分的理由”解。
His parents may well be proud of him. 他的父母以他为骄傲，是有理由的。
He may well say so. 他说得对。
B. may/might as well+动词原形+as+动词原形，意指“与其……还不如……”，其中第二个as表示“与其”，may/might as well表示“还不如”。
may/might as well（还不如……）as...（与其……）
may和might并无现在时和过去时的分别，要说有所不同，则是may表示的可能性比might表示的要大。如：
One may as well not know a thing at all as know it imperfectly. 对一件事情，与其一知半解，还不如完全不知的好。
You might as well throw the money into the sea as spend it on the stock market. 你与其把这笔钱花在股票市场上还不如把钱扔进海里。
有时候可在may/might as well之间加上just，以加强语气。如：
You might just as well act it as say it. 你与其那样说还不如付诸行动更好些。
有时候，第二个as引导的部分可全部省掉，句意为“还是……好”，或“还不如……”，如：
You may just as well tell me the truth. 你还是把事实真相告诉我为好。
There is nothing to do, so I may as well go to bed. 我没什么事要做，所以还不如上床睡觉。
3. have to和must
1 have to和must都表示必须，但二者有些区别。
have to侧重于客观需要，表示由于客观环境的原因而不得不做某事；must则侧重说话人的主观意志，表示主观上说话者认为有必要做某事。试比较：
I must learn the English language well.［表示主观上想把英语学好的意志］
I have to learn the English language well.［客观需要，可能由于工作需要或要去欧美国家深造一段时期等客观原因］
You must write the feasibility report yourself.Im afraid Im not in a position to help you. 我恐怕帮不了你。［说话人的意志］
You have to write the feasibility report（可行性报告）yourself. Nobody can help you.［表客观情况所迫］
2 have to可用于不同的时态，也可与情态动词连用，并可用于被动语态。
We had to put off the track meet because of the bad weather. 因天气不好我们不得不推迟田径运动会。［用于过去时，表客观环境因素］
We will have to come up with the design scheme today. 我们今天得交出该设计方案。［表将来时］
The work will have to be completed before the 10th. 这项工作得在10号前完成。［用于将来时被动语态］
He has been having to stay up late to finish his book for the last few weeks. 近几周来，他必须一直熬夜以完成他的书。［用于现在完成进行时］
My husband is always having to go on a business trip. 我先生总是要经常出差。［用于现在进行时］
Its getting late; we will have to be going. 时间已不早，我们得走了。［用于将来进行时］
▶▶ 而must一般只用于现在时中，也可用在将来时；在间接引语及宾语从句中也可表示过去时，如：
All pedestrians must cross this road by the footbridge. 所有行人必须由天桥穿越这条马路。［表现在时］（“天桥”还可用pedestrian bridge或overhead walkway来表示）
Must we finish the job before tomorrow noon? 我们一定得在明天中午前完成这个工作吗？［表将来时］
Im afraid we must be going, or well not be able to catch the last bus. 我看我们得走了，否则我们将赶不上末班车了。［表现在进行时］
3 must作情态动词可表示主观推测，而 have to 则无此用法。must表示观推测时可用于各种时态。
A. 现在时。
There must be something wrong with the car.I cant start it. 这汽车准是出了毛病，它发动不起来了。
B. 现在进行时。
Dont take it seriously. He must be joking. 别当真，他准是在开开玩笑而已。
C. 过去时。
Mrs. Crook realized that it must be the man from the Electricity Board who had come to read the meter. 柯鲁克夫人意识到来者准是电力公司的人来抄电表的。［用在宾语从句中］
Yesterday morning I told my parents that I must call on an old friend of mine at once. 昨天早晨我告诉我父母说我得立刻去拜访我的一位老朋友。［用于间接引语中表过去式时，must比had to更符合习惯用法］
注：有时候在一定的语境中，虽然没有间接引语的形式但却含有间接引语的意味，这时如表过去式也倾向于用must，如：
Before going to bed last night, I considered how I should spend the next day. First, I must finish my composition.［这里的I must含有I thought I must之意］
D. 表示对过去情况的肯定推测用must have+过去分词，但不能用have to+过去分词。
You must have read a lot of Maughams novels, or you couldnt have talked so much about that famous British writer at yesterdays seminar. 你肯定以前读过毛姆的很多小说；不然，你不可能在昨天的研讨班上谈那么多关于那位著名英国作家的情况。
He left about two oclock.Its five now. He must have got home.
他两点钟走的，现在已是5点；他肯定已到家了。
E. 表过去完成进行时，用must have been+现在分词，表持续性动作，但不能用have to。
It must have been snowing all night. All the trees in the garden are covered with snow. 雪肯定下了整整一夜，花园里所有的树木都盖满了雪。
F. must表“必须”时，否定式不是must not，而是do not have to或neednt。
—Must I work overtime（加班）tonight?
作“不必”解，must的否定式。
—No, you dont have to.
No, you havent got to.
No, you dont need to.
must not作“不许，不准，禁止”解，相当于be not to。如：
你不可如此顶撞你的父母。
You mustnt answer back to your parents like that.
You are not to answer back to your parents like that.
G. must表示的推测含有极有把握的意思，通常只用于肯定式中，其否定和疑问式多用can/could来表示。
He must be at home. He cant be in the office.［cant be是must现在时的否定式］
H. must have+过去分词表示对过去行为、动作或状态的推测，它相应的否定式是can not have/could not have+过去分词。
He was at home all day yesterday, so he cant/couldnt have got involved in the bank robbery yesterday afternoon. 他昨天一整天待在家里，因而不可能参与昨天下午发生的那桩银行抢劫案。
I. must needs和needs must。
① must needs和needs must表示“必须，不得不”解，其中needs是副词，=of necessity或necessarily。
I must needs/needs must do the experiment carefully. 我必须仔细地做这个实验。
② must needs还可作“偏偏”解，但needs must则不能表示这一意思。
My wife must needs talk to me when I dont care to talk. 我太太偏偏在我不想谈话的时候和我谈话。
J. must的两个常用表达法
① What must be...：表注定要发生的意思
What must be will be. 注定要发生的事总要发生。
② If you must+与主句句意相同的动词（通常省略）：表无奈的意思。
A: Can I smoke here?
B: If you must. 如果你一定要抽的话（那就抽吧）［表无奈］
A: Who is it that you care for? 你爱的到底是谁？
B: If you must know, I love Jimmy deeply. 如果你一定要知道（那我只好照实告诉你），我深爱着杰米。
K. must在现代英语中还可作名词，作“必不可少的东西”解。
His new kungfu novel is a must for all lovers of Chinese martial arts. 他新出版的武侠小说是所有中国武术爱好者的必读书。
4. 情态动词need和行为动词need
1 情态动词need。
need作情态动词时有以下几个特点：
① 没有人称和数的变化。
② 后接动词原形（即不带to的不定式）。
③ 否定式为neednt，作“不必”解。
④ 用于疑问句时不用do，does或did。
例如：
He neednt come if he is busy. 他如果忙就不必来了。
Need I repeat what I said just now? 要我重复一下我刚才讲的话吗？
He has gone to the country to recuperate.He never need know. 他已去乡下养病去了，他就不需要知道了。
Nobody need be afraid of developing AIDS. 谁都不必害怕患上艾滋病。
I need hardly say that the experiment is very important and admits of no negligence. 我用不着说，这项实验非常重要，容不得半点疏忽。
注1：need作为情态动词也可用在宾语从句中，即使主句的谓语动词是过去时，need的形式还是不变。如：
The landlord said I need not pay the rent till the 10th. 房东说我不必在10日前付房租/我到10日付房租就可以了。
注2：need的肯定回答是must，否定回答是neednt。如：
A: Need I hurry her into leaving?
B: No, you neednt.（否定）
Yes, you must.（肯定）
注3：must的否定回答也是neednt。如：
A: Must we hand in the homework today?
B: No, you neednt.
▶▶ “neednt have+过去分词”表示过去原本不必做的事情却做了。如：
The weather here is very warm. We neednt have packed these woolen sweaters. 这里天气很热，我们原本不需要带上这些羊毛衫的。
Your son is doing fine at school. You neednt have been worrying so much about him. 你儿子在学校里表现很好，你不必一直为他这么担心。
▶▶ “need have+过去分词”可用于：
① 疑问句中，表示“需要这么/那么……吗？”如：
Need you have worked so hard? 你需要这么辛苦吗？［含有“你条件很好，干吗还要那么劳累辛苦呢？”］
② 用于比较结构中，表示过去，意指“不必……/没有必要……”如：
Last night, you drove faster than you need have done. That was unsafe. 昨晚你没有必要把车开得那么快，那很不安全。
You were more careful than you need have been in doing a job like this. 做像这样的工作，你没有必要那么小心的。
2 行为动词need。
A. 用法和其他行为动词一样。
need作行为动词时有人称和数的变化，后接带to的不定式，在否定句中它前面需按实际需要加doesnt，dont or didnt，在疑问句中句首必须按实际情况加Do，Does或Did。如：
You need to sum up your good experience in this aspect. 你需要总结一下你在这方面的好的经验。
He needs to finish his work report today. 他需要今天完成他的工作报告。
All a company manager needs to have is foresight. 公司经理所需要具备的是预见性。
Do I need to tell him about it? 我需要把这件事告诉他吗？
Does he need to print two or three copies for you? 需要他为你打印两三份副本吗？
Did the man in question need to go to hospital this morning? He only had a few bruises. 此人今天上午需去医院吗？他只是有点碰伤而已。
B. need作行为动词时可接动名词或不定式。
① 接动名词时，动名词须是主动语态，但它的意思一定是被动的，如：
That naughty boy needs spanking（不能用being spanked）. 那个顽皮的男孩需打一顿屁股才行。［这里的needs不是表男孩的主观需要，而是表客观需要，即不打他几下屁股他是不会听话的］
② 接不定式时，不定式须是被动语态。
This difficult sentence needs to be explained（不能用to explain）in detail. 这个难句需要作详细解释。［这里，不定式表示的是主观需要，即难句本身需要给以详细解释］
在实际应用中，need加上后面词语表被动意义时必须用主动态的动名词或被动态的不定式，如：
Your shoes need cleaning=Your shoes need to be cleaned.
My watch needs winding up（上发条）=My watch needs to be wound up.
Your room needs cleaning=Your room needs to be cleaned.
C. need和want一样，后面可接复合宾语。
例如：
We need the work done within two hours.Please put your back into it. 我们需在两小时内把这项工作完成，请加把劲。
We need you over to help our children with their mathematics lessons. 我们需要你过来帮我们的孩子复习数学功课。
We need you to solve that technical problem. 我们需要你解决那个技术问题。
5. 情态动词dare和行为动词dare
1 dare作情态动词。
A. dare作情态动词时无人称和数的变化，后接动词原形，表过去时形式也不变；它的否定形式一概是dare not+动词原形。用于疑问句首不用Do，Does或Did。如：
The late managing director was hot-tempered; no one dare oppose him. 前任执行董事脾气火暴，没人敢反对他。
She is haughty; he dare not ask her out. 她很傲慢，他不敢约她出去。
Dare you contradict what your superior says? 你敢顶撞你的上级吗？
How dare he take my laptop computer without even asking! 他怎么敢不问一声就把我的手提电脑拿走！
注：情态动词dare表过去时形式不变，但在文学语言等正式文体中，dare也可改用其过去式dared，但仅限于表示否定意义。如：
No one dared utter a sound when he flew into a rage. 他大发雷霆时没人敢吭声。
We hardly dared breathe as the president of the corporation walked into our office. 公司总裁走进我们办公室时，我们几乎都不敢喘气了。
以上两例都系正式文体，在日常文体中dared都用dare。
B. 情态动词dare也可用于完成体。
即dare have/darent have+过去分词，表过去想做而不敢做或过去不敢做而现在敢做的事情。如：
I darent have criticized him in the past, but I think I dare now. 我过去不敢批评他，但我想我现在敢这么做了。
Dare he have done it without your permission? 他当时没有你的同意敢做这事吗？
C. 情态动词dare可用于虚拟语气中。
If you dare swim across the English Channel, you would be our school hero. 你如敢游过英吉利海峡，你就是我们学校的英雄了。［虚拟语气，表示同现在事实相反］
Foreign powers darent have bullied us if China had been powerful. 如果当时中国强大，列强就不敢欺侮我们了。［虚拟语气，同过去事实相反］
D. 情态动词dare的三个习语。
I dare say 以为，相信
I dare say you are Japanese. 我看你是日本人。
注1：I dare say也可置于句末。在现代英语里dare say可连写。如：
You are night, I dare say. 我认为你是对的。［置于句末］
I daresay you are American. 我想你是美国人。［daresay连写］
注2：I dare say有它的否定式，是I darent say，如I darent say so. 我不敢这么说。
Dont you dare 你敢……
Dont you dare tell my father about my smoking! 你敢把我吸烟的事告诉我爸爸！
Dont you dare touch the boy! 你敢动这男孩的一根毫毛！
注：“Dont you dare!”也可独立使用，意指“你敢！”，如：
A: Im going to tell your teacher about the gambling. 我要把你赌博的事告诉你老师。
B: Dont you dare! 你敢！
祈使句+if you dare! 你要是敢就……！如：
Quit your job if you dare! 你要是敢就炒你鱿鱼！
Touch me if you dare! 你要是敢就碰我！
2 dare作行为动词时所表示的一些主要词义。
① 敢（做某事）：
He is terrific, daring to confront the tough with toughness. 他真了不起，敢于硬碰硬。
He dares to accuse his superior of corruption. 他敢于指控他的上级有腐败行为。
② 敢于面对……
I will dare any difficulties standing in my way. 我敢于面对前进道路上的各种困难。
③ 向……挑战（往往是带有危险的事情）：
He dared me to jump over the stream. 他向我挑战跳过那条小溪。
