五. shall和should的用法。

1. shall用于第一人称疑问句。表示征求对方意见。

What shall we do this evening?

Shall I open the window?

2. shall 用语第三人称疑问句中，表示说话人征求对方的意见或向对方请示。

When shall he be able to leave the hospital?

3. shall用于第二、三人称的陈述句，表示说话人给对方的“命令、警告、允诺或威胁”。

You shall fail if you don’t work harder.

He shall have the book when I finish reading.

He shall be punished.

4. should表示劝告、建议、命令，其同义词是ought to，在疑问句中，通常用should代替ought to.

You should go to class right away.

Should I open the window?

5. should + have +done应该做的事实上没做;shouldn’t have done不该做的事却已经做了，常含有责备的意思。

You should have started earlier this morning.

You shouldn’t have treated her like that.

六. will和would的用法。

1. 用于疑问句表示请求、建议等，would比will的语气更加委婉。

Will you please give me a hand?

Would you mind my smoking here?

2. 表示意志、愿望和决心。

I will never do that again.

They asked us if we would do that again.

3. 用“will be”和“will have done”的结构表示推测，主要用于二、三人称，前者表示对目前的情况的推测，后者表示对已经完成的动作或事态的推测。

This will be the book you want.

He will have arrived by now.

4. would可表示过去反复发生的动作或某种倾向，表示过去习惯时比used to正式，同时它没有“现在已无此习惯”的含义。

I would visit him during my vacation.

The patient would not recover.

5. 表示料想或猜想。

He would be your new teacher.

He would not come any more.