2. 不定式的语法功能
①.不定式做主语，一般用it当形式主语，把作主语的不定式短语后置。
It took me only five minutes to finish the job.
②.不定式作表语一般表示具体动作，特别是表示将来的动作。To do two things at a time is to do neither．What I would suggest is to start work at once. 【注意】如果主语是不定式（表示条件），表语也是不定式（表示结果）。
To see is to believe. To work means to earn a living． 如果主语是以
aim，duty，hope，idea，happiness，job，plan，problem，purpose，
thing，wish等为中心的名词，或以what引导的名词性从句，不定式作表语是对主语起补充说明作用。
His wish is to buy a luxurious car in the near future．
The most important thing is to negotiate with them about the future of the plant．
③.不定式作定语
?不定式与其所修饰的名词可能是主谓关系
He was the last one to leave school yesterday． ?不定式与其所修饰的名词可能是动宾关系
She has a lot of work to do in the morning． 【注意】
?不及物动词构成的不定式做定语，要加上适当的介词和被修饰的名词形成逻辑上的动
宾关系，这里的介词不能省去。I need a pen to write with． There is nothing to worry about．
?不定式修饰一些表示方向、原因、时间、机会、权利等抽象名词如：
ability能力，本领; drive赶，驾驶; movement运动; ambition抱负; effort努力，尝试; need需求; campaign战役，运动; failure失败，不及格; opportunity机会; chance机会; force力; promise许诺; courage勇气; intention意向; reason理由; decision决定; method方法; light光 determination决心; motive动机struggle奋斗; tendency倾向，趋势; wish希望.
His wish to buy a car came true．
?被修饰的名词前有序数词、形容词最高级或next，second, last, only和not a，the等限
定词时候，只能用不定式。
He is always the first to come and the last to leave．
?不定代词something, nothing, little, much, a lot 等习惯上用不定式做定语。
John will do anything but work on a farm．
?如果其动词要求用不定式做宾语，或者其形容词要求接不定式做补语，则相应的名词
一般用不定式做定语。
tend to do = tendency to do；decide to do = decision to do；be curious to do = curiosity to do
【注意】不定式作定语时的时间关系，一般来说，不定式所表示的动作发生在谓语动词所
表示的动作之后。
Do you want to see the doctor to be sent for from Beijing?
④.动词不定式作状语常常表示目的。
They stood by the roadside talking about the plan．(伴随)They stood by the roadside to talk about the plan． (目的)【注意】
?下面一些句型是不定式做状语时候应该注意的。
not / never too…to, too…not to , but / only too… to, too ready / eager / apt / inclined to表示肯定意义。
?不定式做状语时，其逻辑主语一般为句子的主语，否则用for引导主语。
3. 疑问词+不定式结构
疑问词who，what，which，when，where和how后加不定式可构成一种特殊的不定式短语。它在句中可以用作主语、宾语、表语和双重宾语。如：When to start has not been decided． (主语)I don’t know what to do． (宾语)The difficulty was how to cross the river． (表语)
I can tell you where to get this book. （双重宾语）【注意】
?有时疑问词前可用介词，
I have no idea of how to do it.
?动词know 后面不能直接跟不定式作宾语，只能跟疑问词（如：how, what）+不定式
While still a young boy, Tom knew how to play the piano well and as he grew older, he wrote
operas, the most famous of which is Carmen.
4. 不带to的不定式
①.在表示生理感觉的动词后的不定式不带to。这类词有：
feel 觉得 observe 注意到 overhear 听到 watch 注视 listen to听 perceive察觉，感知notice注意 see看见 look at看 hear听
On seeing the young child fell into the lake，Eric sprang to his feet，and went on the rescue.②.另一类是某些使役动词，如make, let，have等。
I would have you know that I am ill． 【注意】
?上述感觉动词与使役动词转换为被动结构时．其后的不定式一般需带to.
The boy was made to go to bed early.
?在动词find与help之后，不定式可带to亦可不带to.
He was surprised to find the sheep (to) break fence at this season．③.在do nothing／anything／everything but (except) 结构中。Last night I did nothing but watch TV．
When the streets are full of melting snow, you cannot help but get your shoes wet.
但是，如果谓语动词不是“do nothing，anything，everything”，那么but (except) 所跟的不定式则仍须带to。
The doctor told him nothing but to stop smoking．
5. 不定式的逻辑主语
①.for +名词(或代词宾格) 引出的逻辑主语。
I found it impossible for him to do the job alone．
②.在表示人物性格、特性等的形容词后面，常用of引出不定式的逻辑主语。这类词主要
有：absurd, bold, brave, courageous, careful, careless, clever, wise, foolish, silly, stupid, good, nice, kind, thoughtful, considerate, greedy, generous, honest, modest, polite, rude, cruel, selfish, wicked, wrong等。It was wise of him to do that．
③.间或也可用for + there to be表示（而且there后面的不定式只能是to be）。It’s a great pity for there to be much trouble in the company.
六、虚拟语气
虚拟语气是英语三级考试的必考知识点之一，也是体现英汉语言习惯区别的一个语法现象。在汉语里表示假设虚拟的情况常用一些虚词来表示，例如“假设”、“如果”等等；而英文中表示虚拟的情况不但有虚词的提示，谓语动词也要相应的变化。虚拟语气的基本作用是：
1. 表达假设的情况，与事实相反； 2. 表达异想天开很难实现的愿望；3. 表达建议、命令、劝告等语气。
1. 虚拟语气的基本形式和用法
虚拟(条件)语气中，主句与从句中谓语动词的形式可分为下面三类
假设类型条件从句
与现在事实相反与过去事实相反与将来事实可能相反
If+动词的过去式If+ had+-ed分词 If+ were to+动词原形If+ should+动词原形
假设类型从句谓语动词形式
主句谓语动词形式
would(should)+动词原形 would(should)+have+-ed分词would(should)+动词原形
①.Mary said to me, “Had I seen your bag, I _____ it to you.”
A. will return B. must return C. could return D. would have returned D
②.I would ask George to lend us the money if I _____ him.
A. had known B. have known C. knew D. know C
③.If Bob____ with us; he would have had a good time.
A. would come B. would have come C. had come D. came C
【答案】
【答案】
【答案】
2. 省略if的虚拟形式
在虚拟条件句中，如谓语包含were，had，should等词，则可以把这些词放到主语前
面，省略if。①.__________ the advice of his friends, he would not have suffered such a heavy loss in his
business.
A. If he took B. If he should take C. Were he to take D. Had he taken D
【答案】
②.__________, I should ask them some questions. A. Should they come to us B. If they come to us
C. Were they come to us A
③.__________ you were busy, I wouldn't have bothered you with my questions.
A. If I realized B. Had I realized C. Did I have realized that D. As I realized 【答案】B
D. Had they come to us
【答案】
3. 含蓄条件句
有时一个假设的情况不用条件从句表示，而用其它方式来表示，这样的句子叫含蓄条件句。常用with，without，but for, or, otherwise。
①.Without heat and sunlight, plants on the earth ______ well.
A. would not grow B. will not grow C. had not grown D. would not be grown A
【答案】
②.But for my classmates' help, I _____ the work in time.
A. did not finish B. could not finish C. will not finish D. would not have finished 【答案】D③.But for the rain, we _____ a nice holiday.
A. should have B. would have had C. would have D. will have had 【答案】B
4. 错综时间条件句
从句和主句中所表示的动作发生的时间是不一致的，这时就要根据其所表示的时间来进行调整。
?If I were you，I would have gone to see the doctor．
（从句与现在事实相反，主句与过去事实相反）
?If you had gone to see the doctor，you would be all right now．
（从句与过去事实相反，主句与现在事实相反）
5. 特殊词或结构中的虚拟语气
①.以wish (that) 引导的表示“愿望”的宾语从句
wish后的宾语从句中要用虚拟语气，表示现在或将来的愿望用：主语＋wish ＋从句 (主语＋过去时)；表示一个过去没有实现的愿望用：主语＋wish +从句 (主语＋过去完成时)。
I didn’t go to the party, but I do wish I _____ there.
A. were B. would be C. had been D. will be C
Peter wishes that he _____ law instead of literature when he was in college.A．could study B. studied C. had studied D. would study C
【答案】【答案】
②.if only +句子(过去时/过去完成时)“要是…就好了”
If only 后面的句子如果是对现在或将来情况的虚拟，用过去时did ；如果是对过去情况的虚拟，用过去完成时had done . 要注意与if 区别，if 只表示假设，“如果”，用真实语气；而if only 表示不可能实现的情况，用虚拟语气。If only the alarm clock had rung. (对过去虚拟)
If only I were rich. (对现在虚拟)
③.would rather＋句子(过去时)
表示宁愿、宁可的意愿，语气比较婉转。后接过去式。
I am too busy these days. I would rather all of you _____ next month for a dinner.A. come B. would come C. came D. have come I’d _____ you didn’t touch that, if you don’t mind.
【答案】C
A. rather B. better C. happier D. further 【答案】A④.it is time(that)，it is high time (that)…句型中，谓语动词用过去时，表示早该做而未做的
事，意思是该……了、早该……了.
Let’s finish our homework in a few seconds; it's time we __________.A. played football B. will play football C. play football D. are playing football 【答案】ADon’t you think it is time you _____ smoking?
A. give up B. gave up C. would give up D. should give up 【答案】B⑤.以as if，as though引导的从句
在as if，as though引导的从句中，如果谈论的是不可能或不真实的情况时，它们所引用的状语从句要用虚拟语气，动词形式和wish后面的从句动词形式变化相同。He talks as if he _____ everything in the world.A. knows B. knew C. had known D. would have known
【答案】B
6. should+动词原形及should的省略
①.一些表示建议、要求、命令等的动词本身隐含说话者主观的意见。因此这些动词(或其
变形，如名词，形容词，分词等) 后面的从句应使用虚拟语气，即“should do”结构，其中的“should”常被省略。
表“提议、建议”的动词：suggest, advise, propose, recommend, move (提议);表“要求、主张”的动词：insist, require, request, demand , desire ;表“命令”的动词： order, command.
I don’t think it advisable that Tom _____ to the job since he has no experience.A. be assigned B. is assigned C. will be assigned D. has been assigned His mother insisted that he _____ the coat when going out.
【答案】A
A. put on B. puts on C. to put D. putting on 【答案】A
The doctor advised that Mr. Malan _____ an operation right away so as to save his life.
A. had B. would have C. have D. was going to have 【答案】C ②.It is necessary / important / essential / vital / urgent / surprising / amazing that引导的主语从
句中，从句的谓语动词要用should+原形动词，should也可以省略。此类形容词的特点是表示重要性或吃惊。
It is vital that enough money _____ collected to get the project started. A. is B. be C must be D can be It’s urgent that a meeting _____ before the final decision is made.
【答案】B
A. will be arranged B. must be arranged C. be arranged D. would be arranged【答案】C③.以in case, lest, for fear that引起的状语从句，表示“以防，以免”。其形式为should+动词
原形。
He took his raincoat with him in case it should rain.
2. 部分倒装
[VIP专享]三级考前语法精要
