ought to/should

1. 表示义务，"应该"，用于各种人称

例句：(1) You________ be polite to your teacher.

(2) You__________ spend so much time playing computer games.

2.表示推测，"想必，估计"的意思．

例句：If they start today, they _________ arrive there in two days.

3.表示与想象的不一样"照说应该......"

例句：I wonder where Mary is she ________ be here now.

4.在某些从句中，表示虚拟语气．

例句：(1) He suggested that I (______) go to shanghai tomorrow.

　(2) He demanded that we (_______) solve the problem at once.

5.表示惊讶，忧虑，惋惜等感情色彩．

例句：I am surprised he should eat so little every day.

have to/must

　have to 表示客观需求

　must 表示主观愿望

例句：(1) Everyone _______ go to school at the age of 7 in the country.

　　　　　(2)We ______wok hard to make our country strong and rich.

(iii) Certainty might/may/could/should/ought to/will /must

例句：(1) She might win a medal at the Olympics.

(2)She may be at home now.

(3) She could read and write at the age of 4.

(4) She should come to join us.

(5) She ought to/will /must help me whenever I am in trouble.

(iv) Permission ------- can /could/may/might

例句：(1) A : Can I watch the Olympics ?

　　　　　　B: Yes, you can.? /No, you can't.

　　　(2) A: May I have a look at you photo?

B: Yes, you can./ No, you mustn't./No, you'd better not.

Could比can 更委婉，might比may 更委婉

Step 7 Ask students to read Part 2 about the modal verbs of making requests, suggestions or offers, and give advice and read some examples.

Step 8 Additional points:

1. 情态动词表示推测的用法------情态动词must, can, could, may, might都可用来表示推测.

　(1) must所表示的可能性最大，最有把握，意为"一定"。

　(2) can和could主要用于否定句和疑问句中 , can't或couldn't 表示"不可能"

(3) may 和 might表示现在或将来可能发生的动作或情况，主要用于肯定句中，might相对于may 来说，表示的可能性更小一些。

2. 表推测的重要句型：

　(1) 表示对现在或将来情况的推测、判断用"must + do "

　(2) 表示对过去的情况或已经发生的事情进行推测、判断用"must + have +done"

　(3) 表示对现在正在进行情况进行推测、判断用"must + be +doing "

Step 9 其它情态动词的用法

(I) need and dare