Suggested answers:

Then by lunchtime they would all be sold. (possibility)

By now his restaurant ought to be full of people. (possibility)

What could have happened? (possibility)

Something terrible must have happened if... (guessing)

I'll help you lose weight... (intention)

He could not believe his eyes. (ability)

Perhaps he should go to the library and find out. (duty)

He could not have Yong Hui getting away with telling people lies! (intention)

He had better do some research. (duty)

Even though her customers might get thin after eating Yong Hui's food. (possibility)

They would become tired very quickly. (possibility)

...could win his customer back. (ability)

Step Ⅲ Explain the meaning and basic usage of the following modal verbs:

Modal verbs Function & Examples ought to

ought no to In most occasions, ought to means should and ought not to means shouldn't.

eg: You ought to (should) finish the paper on time.

You ought not to (shouldn't) waste all you time playing video games. have to It shows necessity, which is impersonal but for a rule or a situation while must usually shows strong order from a person.

eg: I have to go now or I will miss the bus. don't have to

don't need to They show not necessary to do something.

eg: You don't have to (you don't need to) read the whole book-you can read just some chapters if you don't have time. mustn't It shows prohibition.

eg: The little mustn't play with the knife-it is too dangerous. Step Ⅳ Using proper modal verbs to fill in the conversations. Exercise 2 and Exercise 1 on page 50.

1. Choose suitable modal verbs from below to compete the following dialogues. There may be more than one possibilities.

ought/oughtn't to should/shouldn't mustn't

needn't(don't have to) will can/can't ① SAM: How can I grow thinner, Mum?

MUM: Well, you __________ eat food with plenty of fiber that helps you digest better and you __________ stop drinking cola or eating sweet food.

SAM: Does it mean I __________ eat my favorite fried chicken any more?

MUM: Not exactly, if you love fried chicken, you __________ give it up. Just eat it less often. You __________ worry too much: a little fried chicken __________ do you good!

② DOCTOR: You are sick because you've eaten poisonous mushrooms. Where did you get them?

LUCY: I picked them in the forest. I know we __________ eat fresh vegetables.

DOCTOR: Oh, but you __________ eat them until you're sure they are not poisonous.

LUCY: Thank you, doctor. I will be more careful next time.

③ CHARLES: I wish I could see things clearly in the dark.