Ok, I will do it.

Can I help you, sir?

I am checking out. Could you give me the bill?

Of course we can wait.

Could it be the charge for the fruit?

I can't help thinking of it.

Must I go with you? No, you needn't.

You mustn't forget your medical card.

Oh, it is wet outside. It must have rained yesterday.

So it must be slippery outside. Do be careful!

You needn't have told me that much.

I dare not say it is ugly.

How dare you say so?

Tip:

1) shall表示发言者的意志,包括诺言、决心、强制等; shall用于询问对方的意向。

2) should表示义务，责任等。

3) will用于第二人称疑问句中,询问对方意志或请求。will+原形动词用于所有人称,表意愿。would +原形动词表示过去一段时间的习惯。

4) can, could在口语中相当于may, might,表示许可。 can, could 表示能力,相当于be able to。 can, could表示怀疑、推测,一般用于疑问句或否定句。can,could用于惯用语。can't help或couldn't help+动名词表示不得不、忍不住。

5) must表示必须、义务等,强调主观因素。 need可以对must引导的一般疑问句作否定回答。 must的否定式表示不准,禁止等意思。 must+have+过去分词表示对过去情况的推断。must+原形动词表示对现在情况的推断。 needn't+have+过去分词表示过去不必做却已经做了的事。

6) dare作为情态助动词，一般只能用于疑问句或否定句中。

5. A phrasal auxiliary verb（have (got) to, had better/would sooner/rather (... than)/cannot (help) but/be (not) to/be supposed to/ought to/used to/be about to/be able to ...）

It's getting late. I've (got) to go now.

You don't have to take off your shoes.

Many countries would rather be cautious with this new technology.

The tickets had been sold out, so I could not (help) but go back home.

The children are supposed to be at school before 8 a.m.

I used to love cats but not now, because I was once attacked by a big black cat.

He didn't use to smoke when he was younger.

Did he use to come as often as he does now?

Tip:

have to 强调客观因素。would rather表示宁愿做某事。could not (help) but只能做某事。are supposed to应该做某事。used to 表示过去常常做某事。

清楚地分类呈现助动词，便于学生学习、记忆，为灵活运用助动词打好基础。

Step 4 Practice (PPT 25-26)

Exercises on Page 41 in the textbook.