I'm learning to skate on real ice.我正在真正的冰上学滑冰。
He found it very difficult to get to sleep.他发现入睡很困难。
He came to give us a talk yesterday.他昨天来给我们作了个报告。
Mrs Brown went to see her doctor.布朗夫人去看她的医生了。
三、tell，ask，want，order，get，wish，warn，teach，invite等动词后常跟不定式作宾语的补足语，构成tell/ask……sb to do sth(“告诉/请……某人做某事”)结构。例如：
Could you ask him to call me，please?请你让他给我打个电话，好吗?
[特别提醒]使役动词let，make，have等，感官动词see，hear，feel，watch，notice，look at，listen to等，后常跟不带to的不定式作宾语补足语。例如：
A woman saw it happen when she was walking past.一位妇女路过时看到(它掉下)了。
We often heard her sing in the next room.我们经常听到她在隔壁唱歌。
He was made to do it.他被迫做这件事。
She was often heard to sing in the next room.经常听到她在隔壁唱歌。
I have a lot of work to do.我有许多事情要做。
It is right to give up smoking.戒烟是有益的。
To him，the first important thing was to save lives.对他来说，最重要的事情就是拯救生命。
His wish is to become a scientist.他的愿望是当一名科学家。
He taught us how to use a computer.他教我们如何使用计算机。
I don't know where to go?我不知道去哪里。
一般式to do to be done
完成式to have done to have been done
进行式to be doing无
完成进行式to have been doing无
My wish is to become a doctor
He seemed to be tired.
She stopped to have a rest.
不定式的被动式(to be done)
The building to be finished next month is for our teachers.
I am going to Beijing,I have something to take to my parents,do you have something to be taken to your parents?
如果谓语表示的动作(情况)发生时,不定式表示动作正在进行,这时候不定式就要用进行式.（to be doing）
They are said to be building another bridge across the street.
They seemed to be talking about something important.
When I went to his home,he happened to be traveling around the world.
I'm glad to be working with you.
如果不定式所表示的动作或状态发生在谓语动词所表示动作或状态之前，就用完成式(to have done)；若是在此基础上的被动含义，就用完成被动式(to have been done).
He is said to have written a novel about the Long March.
He thought it a pity not to have invited us.
The assistant seemed to have been fired.
He is said to have been taught French when he was a child.
Einstein is said to have built up his theory when he was in his twenties.
They are said to have been collecting folk song in Xinjiang.
We're happy to have been working with the experts all the month.
e.g:To finish the building in a month is difficult.
To do such things is foolish.
To see is to believe.(对等)
(1)It is/was+adj.+of sb.to do…
(2)It is+adj.+for sb.+to do…
It is easy/difficult/hard/foolish/unwise/right/wrong/unnecessary
(3)it is+a+名词+to do...
It is a pity/a pleasure/a pleasant thing/one's duty/an honor/a shame/a crime/no easy job…to do
It takes(sb.)some time/courage/patience…to do…
It requires courage/patience/hard work…to do…
It is probable for him to come to the meeting.(错）
It is possible for him to come to the meeting.
It is possible/probable that he will come to the meeting.
主语是以aim duty hope idea intention plan job suggestion wish purpose task等为中心词的名词词组或以what引导的名词性从句表示，后面的不定式说明其内容,不定式作表语常表示将来或现在的动作或状态。
eg:My idea is to climb the mountain from the north.
Your mistake was not to write that letter.
What I would suggest is to start work at once.
想要学习早打算（want learn plan）
快准备有希望（prepare hope wish expect）
同意否供选择（agree offer choose）
决定了已答应（decide be determined promise）
e.g.Tom refused to lend me his pen.
We hope to get there before dark.
The girl decided to do it herself.
stop/go on/remember/forget/regret/try/mean/can't help/beusedto
He is the doctor to do the operation.
I have a lot of things to do.
This is the right time to start.
He has no way to go(by).This is the best place to work(at)
He want you to be his assistant.I saw her cross the street.
I felt my blood run cold.What made you think like that?
He was made to clean the windows as a punishment.
Someone was heard to come up the stairs.
They helped me carry the boxes.
This kind of soap will help you to wash the clothes more easily.
They helped(to)carry the furniture upstairs.
[注3]look at及listen to后用作宾补的不定式不带to（这主要是美式英语）。
We have been listening to the radio tell a long story.
That is hard to say.The chair is comfortable to sit in.
e.g.To learn a foreign language well,you must try your best(主语一致)
He came here to attend an important meeting.
He came here in order to see Charlie.
I turned the radio down so as not to disturb him
*但是，置于句首表示目的的不定式可以是to,in order to，但却不可以是so as to.
eg:To draw maps properly,you need a special pen.
In order to draw maps properly,you need a special pen.
To get the best results,use clean water.
To be elected monitor of our class,he gave money to us.
e.g.He bowed to us to thank us for helping him find the way.
He worked day and night,hoping to finish the work beforehand.
e.g.He bought a bicycle to go to town more quickly.
He went home to see his mother.
例外eg:He opened the door for the children to come in.
They sent a man to mend the window.
Would you be so kind as to lend me your bicycle/tell me the time?
I'm not such a fool as to believe that.
The boy is old enough to go to school.
His eyesight is too poor to read such small letters.
⑤only to find,only to be told出乎意料之外的结果
He was too excited to get high marks.
Is this your purpose,to avoid being punished?