（1）可能性

　　I may be busy from tomorrow on.从明天起我可能会忙起来。

　　You may catch sight of the sunrise from here when you get up before 5 in the morning.你在早晨五点钟以前起来，或许能从这儿看到日出。

　　I wondered if they might agree with the idea.我想知道他们是否会同意这种想法。

　　She thought it might be wise to try her luck here.

　　她认为在这儿碰碰运气也不错。

　　（2）表示允许

　　May I come in？我可以进来吗？

　　I'd like to have a smoke here if I may.

　　如果可以的话我想在这儿抽一支烟。

　　The librarian told her that she might return the book to the library in three days.

　　图书馆理员告诉她说，她可以在三天后还那本书。

　　At the press conference ，a news reporter asked the chairman if she might trouble him with a question about Taiwan issue.

　　在记者招待会上，一位新闻记者问大会主席她是否能提一个有关台湾问题方面的问题。

　　（3）may间或用来表示祝愿，也常用于表示目的或让步的状语从句中：

　　May that day come soon .但愿这天早日到来。

　　May you succeed in winning the first prize in the game.

　　祝愿你比赛夺冠成功。

　　May you continue in your efforts and achieve greater successes.

　　祝愿你继续努力并取得更大的成功。

　　（4）表示极有可能发生某事

　　As an auto repairman ,Dick ought to know what is wrong with the car.

　　狄克作为一个汽车修理工总该知道这部车的毛病所在吧。

　　If we set off right now ,we ought to be able to get there in time.

　　如果我们马上出发，我们应当能够按时到达那里。

　　Tomorrow ought to be a nice day for we have such a fine sunset today.

　　今天有这么好的晚霞，明天准是个晴天。

　　need（用于否定句和疑问句）需要

　　There are still one and a half hours to go,we needn‘t be insuch a hurry.

　　还有一个半小时，我们无需如此慌慌张张。

　　I hardly need say how much we missed you.不用说我们是多么想念你啊。

　　Need you go so soon？你需要这么早就去吗？

　　You need have no anxiety on my account.你不必为我而着急。

　　dare ，dared（用于否定句、疑问句和疑问句）敢

　　Dare you stay here alone in the night？ 你敢在夜里呆在这儿吗？

　　Nobody dared mention that matter. 没有人敢提那件事。

　　How dared you say that to her？ 你怎么敢对她说那件事？

　　Even if you dare do it ,I won‘t allow you to because it’s too dangerous.

　　即使你敢做，我也会让你做那件事，因为太危险了。

　　shall 用作情态动词时，适用于第二人称和第三人称。

　　主要表示下面几层意思：

　　(1）许诺

　　You shall hear everything directly you come.你一来就可以听到一切了。

　　"Whatever you want you shall have ,"said the Fairy.

　　仙女说：“你想得到什么，你就可以有什么。”

　　I don't want to be hard on your daughter ;she shan't be pressed.

　　我不想对你女儿太严厉，她不会太受压的。

　　I promise that you shall see her again before long.

　　我保证你不久就能再见到她。

　　（2）命令

　　You shall come to my office immediately.你必须马上来我的办公室。

　　She shall not stay in my garden.她不可以呆在我的花园里。

　　He shall not come into my study. 不许他进我的书房。

　　You shall do as you are told.按告诉你的那么做。

　　（3）决心（表示某事一定会发生）

　　That day shall come.那一天一定会到来。

　　It has been decided that he shall be given the job.

　　肯定给他那份工作的事已经定下来了。

　　This law shall come into effect on January 1st 2001.

　　这个法律于2001年元月1日生效。

　　（4）规定

　　Each competitor shall wear a number .每个参赛者要佩戴一个数字标。

　　The renter shall keep the house in a neat and orderly state.

　　租赁者要保持房屋整洁有序。

　　The supplier shall make shipment before October and the purchaser shall make payment within 15 days after receipt of the goods.卖方十月以前装运，买方在收到货物后十五天内付款。

　　should（用作情态动词时，有时表示具体的意思，有时却没有意义。主要用于下面几个方面。）