(1)做形式主语的代词： 不定式做主语, 通常用it充当形式主语, 把做主语的不定式短语后置。 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.
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.
掌握常用不定式做主语补足语的句型。注意不定式表示的动作发生的时间，并采用相应形式。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.
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.
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.
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.
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。
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.
(1)被修饰的名词前有序数词、形容词最高级或next, last, only, not a, the, very等限定词时，该名词用不定式做定语。如：
the first woman to set foot on the moon 第一个登上月球的女性
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.
ambition to do “干……的雄心”→be ambitious to do“有雄心干……”
curiosity to do “对……的好奇心”→be curious to do“对……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.
way, method, reason, time, place, chance, occasion, opportunity, evidence, power, right, movement, drive (运动)，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)不定代词something, nothing, little, much, a lot习惯上用不定式做定语。如：
Though we have made great progress, there is still much to be improved.
(1)in order to(do), so as to(do)结构引导目的状语，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结构做程度状语。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.
常见的不定式动词有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 表示肯定意义。如：
I am only too pleased to hear from you further. 能再听到你的消息，我太高兴了。