不定式(Infinite) : to +V
不定式用法（一）： 1)不定式作主语 ? To say is one thing; to do is another. ? To talk with him is a great pleasure. 上述情况一般不多用，作为考试规范英语，倾向于用先 行词it作形式主语，把不定式后置。 ? It is a great pleasure to talk with him. 不定式的逻辑主语: ? It is quite important for us to read good books during the period of general review. ? It is very kind of you to help me.
不定式作表语 ? To live is to struggle. ? Our plan is to complete the design tomorrow. ? We are to complete the design tomorrow.
不定式作宾语 1 某些及物动词后只能接不定式作宾语: afford, arrange, care, demand, choose, happen, agree, decide, desire, determine, expect, learn, hope, want , promise, pretend, refuse. ? We have learnt to ride the bike. He promised to come. 2 动词+疑问代词(副词)+不定式: what, when, where, which, how, whether ? He does not know when to speak before strangers. ? who(m) to visit. ? which one to choose. ? I will show you what to do.（where to go）.（how to deal with it ? You can decide whether to go forward or stay here. 3 但why/why not +V (后接不带to的不定式) ? I don’t know why argue with him.
不定式作定语：作定语修饰名词或代词，只能作 后置定语。 ? We have a lot of work to do. ? We are facing a lot of difficultiesto overcome during the period of review. 不定式作定语时, 与被修饰的词有动宾关系, 若不 定式是不及物动词, 其后必须有介词。 ? He is a good colleague to work with. ? I had got no place to live in.
不定式作状语 1 目的状语. 为了强调，可用 so as to , in order to ? They work hard to finish this task in time. ? We all get up early so as to catch the first bus. 2 结果状语 ? too….to (太….而不能): The boy is too young to move the box. ? not/never too…to(不太….能)： We are never too old to learn. ? too…not to (很….不会不)： He is too smart not to see your point. ? only/but too = very(很，非常) : He is but too glad to join us. We are only too happy to have you with us. ? too ready/ eager to (时刻准备，急于)： We are only too ready to apply to others the cold wind of criticism. ? enough….to (足够 ….能)： The speed is high enough to catch up with the train. ? not…enough to (不够而不能)：He is not tall enough to reach the top.
不定式作宾补 1 allow, ask, cause, expert, find, imagine, know, tell ,think, want, wish 后接不定式作宾补 ? We know her to be an expert. ? We consider him to be a good officer. 2 feel, notice, hear, see, watch, listen to, look at, have, make, let后 的不定式省略to, help后可省可不省. 但若为被动语态时, to又不可 省略. ? Let