助动词的相关语法（auxiliary verb）
助动词也是动词的一种，它用以表示：可能、应该、愿望、必须……通常放在动词
（verb）或形容词（adjective）之前。它也时常令初学者感到混淆。
一、shall 和 will
1.1 助动词shall/will 的最常用法，就是表示后面的动词属于未来式（future tense）:
第一人称（I、we）用shall:
I shall go tomorrow.
We shall go tomorrow.
第二人称（thou、you）及第三人称（he、she、it、they）都用will:
He will go tomorrow.
She will go tomorrow.
They will go tomorrow.
1.2 如果shall或will并不是用来表示后面的动词是未来式的，那么shall将用在第二及三人称，这时就有“决定、命令、答应”等意思：
You shall obey me.（你要服从我。）
He shall leave the house instantly.（他决定马上离开家。）
You shall have my book.（说这话的人答应把书给对方。）
同样的，will用在第一人称时，就有“决定、答应、情愿”等意思：
I will speak, in spite of you.（不管你怎样，我决定说。）
I will never forsake you.（我永远不会舍弃你。）
二、should和would
上一则拉杂谈谈了助动词shall和will。实际上这两个助动词，以及should和would的用法相当复杂，令我感到有不知从何下手的感觉。现在就shall和will再举一些例子。
shall 用在第一人称（就是 I 或 we） 时：
I shall tell you this evening.（意向）
I shall never do it again.（答应）
Shall I post the letter for you?（问对方的意愿）
shall 用在第二人称（you）或第三人称（he, she, it , they） 时：
You shall never see her again.（意向）
You shall go at once.（命令）
You shall have a reward.（答应）
You shall punished.（恫吓）
Shall he be paid?（问对方的意向）
will 用在第一人称时：
I will work hard.（意向）
I will be obeyed. （命令）
I will help you as much as I can.（答应）
I will punish you.（恫吓）
will 用在第二人称或第三人称时：
You will send in your report on Thursday.（命令）
Whatever you may say, things of this kind will go on.（必然性）
Will you help me?（请求）
Will you tell me about it?（请求）
You will sit here for hours saying nothing.（表示习惯）
三、助动词should 的用法：
3.1 should 用在第一人称时：
I should be glad to see you if you would call tomorrow morning.（条件）
I should be glad to see you.（省略条件子句conditional clause）（条件）
We should sort out this problem at once.（决定）
I think we should check everything again.（劝告）
3.2 should 用在第二人称或第三人称时：
Should you like to see him if he should call on you this evening?（表示将来）
Should you like to see him.（省略条件子句conditional clause）
It's a pity you should always be so busy.（看法）
If you should see Peter, tell him about the match.（可能）
You should apply for a visa right away.（责任）
If it should be fine tomorrow, I shall go out.（条件）
It is a pity that she should be so ill.
3.3 should 用在任何人称时：
I / You/ He/ She/ They should study hard.（义务或责任）
四、助动词would 的用法：
4.1 would 用在第一人称时：
If I could, I would work hard.（意向）
I would be obeyed.（命令）
I would help you as much as I could.（答应）
I would punish you if you should do it again.（恫吓）
4.2 would 用在第二人称或第三人称时：
If you were a bird, you would be able to fly.（将来）
Would you tell me about it?（请求）
Would you help me?（请求）
Would you were with us!（愿望）
He would keep playing with my watch.（持续）
They wouldn't（would not） believe me.（拒绝）
Would you mind if I brought a colleague with me?（许可）
Would you pass the salt please?（请求）
Would you mind waiting a moment?（请求）
Would you like to play golf this Friday?（邀请）
五、MAY
5.1 表示许可（Permission）:
You may go home now.
She may go to the cinema.
You may not go anywhere.
She may not go to the cinema.
May I go to the cinema?
May I use your dictionary?
May I have another cup of coffee?
May I watch television tonight? Yes, you may.
May I leave work at 16:00 hrs.? No, you may not.
5.2 表示可能性（Possibility）：（也可用 might 代替）
China may become a major economic power.
We may go to dinner tonight, I'm not sure.
It may snow tomorrow.
He may not go to Spain this year.
Perhaps I may go with you.
5.3 表示某种祈愿：
May success be yours.
May you return in safety.
May he rest in peace.
May God help us!
5.4 may have 表示“也许曾经”：
He may have missed his train.
5.5 that...may 表示目的：
Teach me that I may be able to learn.
He flatters that he may win power.
