不定式是英语六级考试常见的语法之一，不定时在句子里面可以充当主语、宾语及定于等句子成分，我们一起通过这篇2014年12月英语六级重点语法之不定式来了解一下不定时的用法吧!
1.不定式做主语(1)引导逻辑主语的介词：不定式的逻辑主语一般由介词for引导,但下列表示人的性格行为特征的形容词做表语时, 不定式的逻辑主语则由of引导：
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：
It’s clever of you to have invented such a device.
(2)不定式做主语补足语：
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： be said / reported / thought / believed / known / supposed + to do sth.
2.不定式做宾语掌握要求接不定式做宾语的动词：
afford, arrange, attempt, claim, desire, determine, expect, fail, guarantee, endeavor, intend, pledge, pretend, resolve, request, swear, tend, venture。如：
Even though the children pretended to be asleep, the nurses were not deceived when they came into the room.