动词不定式用列

动词不定式做主语:

to get up early is necessary 早起是必要的
it做形式主语
it's necessary to get up early

动词不定式做宾语

he decided to buy a new car

动词不定式做宾语补足语

I like you to keep everything tidy

疑问词加不定式做宾语

please show us how to do that

动词不定式做表语

his wish is to be a policeman

动词不定式做状定语

we need someone to help
I have many letters to write
如果不定式的动词是不及物动词，后面须加上适当的介词
I am looking for a room to live in.