1. 带to 的不定式： i have come to seek your advice.
2. 不带to 的不定式：what you said made me think.
Eg: he seems to be in good health.
I hope to be back in a couple of days.
一般式 To do To be done
完成式 To have done To have been done
进行式 To be doing /
完成进行式 To have been doing /
will you please call back again in a little while?
Would you like me to interpret for you?
This was thought to be impossible.
His situation was considered to be dangerous.
To compromise appears advisable.
To stop the work now seems impossible.
•it + be + adj. +不定式 （斜体部分为真正的主语）
It is foolish to act like that.
It is hard to say which is better.
•it + be + n. +不定式
It is an honor to meet you.
It is our duty to obey the law.
• it + 动词（宾语） + 不定式
It amazed me to hear that you were leaving.
•④ it + be + 介词短语 + 不定式
It’s beyond me to explain these.
It’s not within my power to change his view.
He agreed to pay $4,000 for the car.
we managed to put the fire out.
God bless you.
It is essential that effective measure (should ) be taken.
•过去虚拟语气---动词be 要用were 的形式
She treated me as though i were a stranger.
I wish i had not done so.
真实条件句 和 虚拟条件句
i will not go to the party unless they invited me.
If you are waiting for a bus you’d better join in the queue.
If i had enough money, i would buy a computer.
If you had arrived a little earlier, you would have seen her.
相当于过去式的形式 Would + 动词原形
Would 有时可由might / could 构成
If i had a map i would lend it to you. (但我没有）
If i lived near my office, i’d walk to work. （我住的不近）
在were 和 should 的从句中，if 有时可省略，但语序要倒装
Were i Tom i would refuse.
Should she be interested, i’ll phone her.
If it were not for 若不是。。。
You wouldn’t be anywhere if it weren’t for Ruth.
I wish I were a bird. 但愿我是一只小鸟。
I wish I knew the answer. 我要是知道答案就好了。
I wish she had taken my advice. 那时她要是接受我的建议就好了。
I wish that I had seen her yesterday. 真希望我昨天见过她。
I wish you would stay an hour longer. 我希望你再呆一个小时。
I wish it could stop raining. 但愿雨能停。
The students hope that their football team will win the game.
I wish I could see him now. 我希望现在就能看到他。（不可能实现）
My advice is that you (should) practice speaking English as often as possible .
The demand is that the composition (should) be written on one side only.
It is my desire that all the members of the family (should) gather once a year.
The suggestion that education (should) be reformed is reasonable.
The teacher treats the pupil as if he were her own child. 这位老师对待这位学生就像自己的亲生孩子一样。（这位学生并不是她的亲生孩子）
I felt as though we had known each other for years. 我感觉我们好像认识多年了。（其实并没有认识多年）
It looks as if it might rain. 天看上去好像要下雨。（不大可能下雨）
He looks as if he is young. 看样子他好像很年轻。（他就是年轻）
He looks as if he were young. 看样子他好像很年轻。（实际上他不年轻）
Please remind me of it again tomorrow in case I (should) forget.
She emphasized it again and again, lest he (should) forget.
We had a meeting and talked the matter over face to face for fear that there should be any misunderstanding.
I shall write down your telephone number so that I may not forget.
They worked harder than usual in order that they could finish the work ahead of time. 为了能提前完成工作，他们比往常更加努力。
We will tell you the truth so that you can judge for yourself.
Though he (should) fail, there would still be hope. 即使他失败了，仍有一线希望。
I should say the same thing even if he were here. 即使他在这里，我还是要这么说。
Whether he (should) succeed or fail, we shall have to do our part.
However hard it might rain rains, we shall go there together.
No matter what his social position (might) be, a man is equal in the eye of the law.
It is time that the children went to bed. 到孩子们睡觉的时间了。
It is high time that we began the meeting. 正是我们开会的时间了。
If only he knew the answer. 他要是知道答案就好了。（用过去时表示现在）
If only I could speak several foreign languages！
If only you had told me the truth before.
If only I had known her earlier! 要是我早点儿认识她就好了！
= I wish I had known her earlier.
I would rather you left today. 我宁可你今天走。
I would prefer he didn't stay here too long.
I would rather I hadn't seen that film yesterday.
I'd rather play tennis than swim. 我宁愿打网球，也不愿游泳。
I'd rather not go to the movies. 我宁愿不去看电影。
Which would you rather have, tea or coffee 你喜欢喝茶，还是咖啡
I'd rather you went home now. 我希望你现在就回家。
I would rather my daughter attended a public school.
Long live the People's Republic of China! 中华人民共和国万岁！
May you be happy! 祝您快乐！
God bless you! 上帝保佑你！
Success attend you! 祝你成功！
The Lord save us! 愿主救我们！
You could answer this email for me. 你可以替我回这个电子邮件。
Could you leave me your telephone number and address
Would you mind opening the window 劳驾把窗子打开，好吗？
You might as well put off the discussion till next week.
相当于过去完成时的形式 Would have + 过去分词
If i had known that you were coming, i would have met you at the airport.
If anything had happened, he would have let us know.
要不是。。。 If it had not been for...
If it had not been for Margaret, i might not have understood.
Had it not been for their support, we could not have won the election.
(Should) + V. → Should 可省略
V.: order, advice, suggestion, proposal, demand, request, desire, suggest, insist, ask, etc.
例：he asks that he be given an opportunity to explain his case.
I advise that he go at once.
1.If only... 要是。。。就好了
If only we had follow your advice!
If only i were to see him again!
2. It is （high） time... 该是。。。的时候了
It is （high） time you bought a new car.