一.不定式做宾语: 1. it作形式宾语:find(think,keep,make...)+it+adj.+(for sb) + to do sth. 动词不定式作宾语且过长时常用it 作形式宾语，而让真正的宾语——不定式断后。例如： The man downstairs found it hard to fall asleep. 2.不定式直接做动词宾语:want(forget,remember,like,love,hate,continue,begin,start,hope,wish....)+ to do sth. I forgot to turn off the lights last night. 二:不定式做主语: 1.It 做形式主语,不定式做真正的主语: 1) It is(was) + adj. +(for sb)+to do sth. It's very dangerous for children to play with fire. 2) It takes(took,will take) sb some time +to do sth. It will take me three days to finish reading the book. 2.不定式直接做主语:To play football in the street is very dangerous for children. 三.不定式做表语:My duty is to look after the kids well. 四.不定式做定语: 作定语时，不定式（短语）常置于被修饰的名词、不定代词等之后。例如： I have lots of things to do today. Would you like to give me something to eat? [提示]如果不定式（短语）是不及物动词，其后应有必要的介词/副词。例如： I found a nice place for him to live in. Please give me some paper (pens) to write on(with). 五.不定式做状语: 1.不定式（短语）常跟在 come， go， run， hurry 等动词后作目的状语；或以“in order to +动词原形”、“so as to +动词原形”等形式出现，或回答 what . . . for？ / why . . . ？问句。例如： -Hi， Peter！ Why are you in such a hurry？ -To catch the 7：30 train. [提示] 有时目的状语可置于句首，意为“为了……”，相当于in order to.例如： To catch the bus， you must get up early. 在stop 后的动词不定式其实是作目的状语，意为“停下来做另一件事”。例如： Let’s stop to have a meal. I know a good restaurant near here. 2.作结果状语的不定式常以“enough to . . . ，only to . . . ， too . . . to . . . ”等形式出场，并能简化成 so . . . that . . . 句式。例如： Liu Mei was so lu...
