To learn English is very important.
It's very important to learn English.
My idea is to ring him up at once.
I have decided to go to Binjiang Primary School.
a. ask, want, teach, tell, know, would like, allow等动词后面接动词不定式作宾语补足语。
如： The policemen asked him to get off the bus.
b. hear, see, look at, feel, watch, notice, listen to等动词后接不带to的动词不定式作宾语补足语。
如： We often see Miss Li clean the classroom.
c. let, make, have这些使役动词后接不带to的动词不定式作宾语补足语。但在被动语态中这些不带to的都须带上to。
如： In those days the bosses often made the workers work day and night.
如： Can you help me (to) carry the heavy bag?
a.与被修饰词有动宾关系。如：I have something important to tell you.但如果不定式动词为不及物动词，后面的介词千万不要省略。
如： Maybe they have three rooms to live in.
如： Mr Liang is always the first to come and the last to leave.
如： I have no time to play cards.
如： I'll go to meet my friend at the railway station.
7.不定式复合结构"for sb. to do sth" 作主语时，常用"It is +adj+ for
of sb. to do sth"的句式。形容词good, bad, polite, unkind, kind, ice, clever,
right, wrong, careful等用"It is +adj +of sb. to do sth."
It's dangerous for you to ride so fast.
It's very kind of you to help me.
8.动词不定式与疑问句who, what, which, when, how, where, whether等连用。
如： I don't know when to start.
He didn't tell me where to go.
I don't know when we'll start.
He didn't tell me where he would go.
如： enjoy, finish, keep, mind, miss(错过),be busy, go on, keep on, be worth, practise等。
如： The peasants are busy picking apples.
Would you mind my opening the door?
如： Lu Jian forgot to post the letter.(该寄但还没做)
Lu Jian forgot posting the letter.(已经寄过信了)
They stopped to sing a song.(停止在做的工作而去做另一件工作)
They stopped singing.(停止正在做的工作)