二、不定式 1.不定式做主語
(1)做形式主語的代詞：
不定式做主語, 通常用it充當(dāng)形式主語, 把做主語的不定式短語后置。 如：
It took me only five minutes to finish the job.
To be frank, it is a great relief to have the task fulfilled in so short a time.
(2)引導(dǎo)邏輯主語的介詞：
不定式的邏輯主語一般由介詞for引導(dǎo),但下列表示人的性格行為特征的形容詞做表語時(shí), 不定式的邏輯主語則由of引導(dǎo)：
absurd, bold, brave, courageous, careful, careless, clever, wise, foolish, silly, stupid, good, nice, kind, thoughtful, considerate, greedy, generous, honest, modest, polite, rude, cruel, selfish, lazy, wicked, wrong。如：
Experts say walking is one of the best ways for a person to stay healthy.
It’s clever of you to have invented such a device.
(3)不定式做主語補(bǔ)足語：
掌握常用不定式做主語補(bǔ)足語的句型。注意不定式表示的動(dòng)作發(fā)生的時(shí)間，并采用相應(yīng)形式。如：
said
reported
thought
be to do sth.
believed
known
supposed
Byron is said to have lived on vinegar and potatoes.
The bank is reported in the local newspaper to have been robbed in broad daylight yesterday.
2.不定式做賓語
(1)必須接不定式做賓語的動(dòng)詞：
掌握要求接不定式做賓語的動(dòng)詞：
agree, afford, aim, arrange, appear, ask, attempt, choose, claim, decide, desire, determine, expect, fail, guarantee, hope, endeavor, intend, long, mean, manage, offer, ought, plan, pledge, pretend, prepare, promise, proceed, prove, resolve, refuse, request, swear, tend, try, venture, wait, wish。如：
Even though the children pretended to be asleep, the nurses were not deceived when they came into the room.
注意:
1)有的動(dòng)詞要求特殊疑問詞+不定式做賓語, 這類動(dòng)詞有：
consider, discover, explain, forget, guess, know, learn, observe, remember, see, tell, understand, wonder，如：
While still a young boy, Bizet knew how to play the piano well and as he grew older, he wrote operas, the most famous of which is Carmen.
2)如果該特殊疑問詞在不定式中做介詞賓語, 介詞往往置于該特殊疑問詞的前面。如:
The professor can hardly find sufficient grounds on which to base his argument in favor of the new theory.
Without facts, we cannot form worthwhile opinion for we need to have factual knowledge upon which to base our thinking.
(2)可以用不定式做賓語補(bǔ)足語(復(fù)合賓語)的動(dòng)詞：
下列動(dòng)詞可以用不定式做賓語補(bǔ)足語(復(fù)合賓語)：
advise, allow, ask, beg, cause, command, compel, enable, determine, encourage, expect, feel, find, force, hate, have, hear, help, inform, invite, let, like, make, mean, need, notice, notify, oblige, order, permit, persuade, remind, request, require, see, send, teach, tell, tempt, trouble, urge, want, warn, watch, wish。
注意：畫線動(dòng)詞后面的不定式不帶to。
如：
Because of the recent accidents, our parents forbid my brother and me to swim in the river unless someone agrees to watch over us.
3.不定式做定語
(1)被修飾的名詞前有序數(shù)詞、形容詞最高級(jí)或next, last, only, not a, the, very等限定詞時(shí)，該名詞用不定式做定語。如：
the first woman to set foot on the moon 第一個(gè)登上月球的女性
(2)如果其動(dòng)詞要求不定式做賓語，相應(yīng)的名詞一般用不定式做定語。如：
tendency to do→tend to do, decision to do→decide to do This book is an attempt to help you use English and recognize how it is used.
(3)如果其形容詞形式要求接不定式做補(bǔ)語，相應(yīng)的名詞一般用不定式做定語。如：
ambition to do “干……的雄心”→be ambitious to do“有雄心干……”
curiosity to do “對(duì)……的好奇心”→be curious to do“對(duì)……好奇”
ability to do“做……的能力”→able to do“有能力做……”
According to Darwin, random changes that enhance a species’ ability to survive are naturally selected and passed on to succeeding generation.
(4)表示方式、原因、時(shí)間、機(jī)會(huì)、權(quán)利等名詞用不定式做定語，這些名詞包括：
way, method, reason, time, place, chance, occasion, opportunity, evidence, power, right, movement, drive (運(yùn)動(dòng))，effort等。如：
I worked so late in the office last night that I hardly had time to catch the last bus.
We appreciate your efforts to bring about a comprehensive solution to the existing problem.
(5)不定代詞something, nothing, little, much, a lot習(xí)慣上用不定式做定語。如：
Though we have made great progress, there is still much to be improved.
4.不定式做狀語
不定式做狀語主要表示目的、程度、結(jié)果、方式。
(1)in order to(do), so as to(do)結(jié)構(gòu)引導(dǎo)目的狀語，so as to不能置于句首。如：
To succeed in a scientific research project, one needs to be persistent .
I advise them to withdraw so as not to get involved.
(2)so…as to, such…as to, enough…to, too…to結(jié)構(gòu)做程度狀語。如：
The solution works only for couples who are self-employed, don’t have small children and get along well enough to spend most of their time together.
The vocabulary and grammatical differences between British and American English are so trivial and few as hardly to be noticed.
(3)不定式做結(jié)果狀語只能出現(xiàn)在句子的末尾，表示不愉快的結(jié)果，有時(shí)用only加強(qiáng)語氣。
常見的不定式動(dòng)詞有find, hear, see, be told, form, give, make, produce等。如：
Greatly agitated, I rushed to the apartment and tried the door, only to find it locked.
(4)not/never too… to, too… not to, but/only too…to, too ready/eager/apt/inclined to 表示肯定意義。如：
I am only too pleased to hear from you further. 能再聽到你的消息，我太高興了。
