用在由so that或

in order that引导目的状语从句中 1. She saved her money in order that she might buy a watch.

　为了买块手表，她节省钱。

2. I am saving my money so that I may go to Australia next winter.

　我正在攒钱，以便明年冬天到澳大利亚去。 表示祝愿 1. May you have a good time.

2. May you succeed. 表示让步 　Try as he may, he cannot find her. 表示建议（和as well连用） 1. We may as well stay where we are.

2. You may as well consult a dictionary.

must 的用法：

用法 例句 表示必须，必要，mustn't (must not) 表示禁止，不准 1. You must come to school early enough for the morning class.

你必须早晨到校上早读课。

2. You mustn't talk to your father like that. 你不能那样对你父亲讲话。 表示主语的肯定推测, "一定""准是"，比may肯定得多 1. The lady can't be only 30. She must be 50.

　那位女士不可只有30岁。她肯定50岁了。

2. The old man must be our history teacher.

　那位老夫子肯定是我们的历史老师。 后面加动词不定式的完成式表示对过去事物的推测 Mike speaks Chinese very well. He must have studied Chinese before.

迈克的汉语很棒,他以前肯定学过汉语的 后面加动词不定式的进行式表示对现在进行事物的推测 　She must be waiting for us.

　她一定在等着我们。 表示推测的否定和疑问结构不能用must须用can 1. The door is locked; she cannot be at home.

　门锁了，她一定不在家。

2. Can the news be true?

　这消息可能是真的吗？

说明 must 和have to 都可以表示必须，但must 着重说话人的主观看法，而have to强调客观需要。 另外，have to 有多种时态形式。如：

1. We must learn at least a foreign language well.

　我们必须学好至少一门外语。

2. Mother was ill, so I had to look after her at home.

　母亲病了，我得在家照顾她。

will/would的用法:

用法 例句 用干各种人称，表示意愿、意志或决心 1. I will do anything my country asks me to do.

　我决心做祖国需要我做的任何事。

2. Xiao Hong said that she would help me with my maths.

　小红说她愿意帮助我学习数学。 用于第二人称的疑问句，表示征求对方的意见或向对方的请求。Would 比will更委婉客气些 1. Will you give this note to Tom as soon as he comes back?

　汤姆一回来，你把便条给他，好吗？

2. Would you mind explaining it again?

　请你能再解释一遍好吗？