1、Unit 4 Exploring literature Grammar and usage Modal verbs How to use modal verbs to describe possibility Jack can swim. I must go now. You can use my pen if you like. They should build more libraries. They must be very tired. (Ability) (Necessity) (Permission) (Suggestion) (Possibility) Functions of
2、 modal verbs A hundred men may pass a field and see only dead grass . (page 45, line 1718) Friends must part. 天下无不散之筵席。 Using modal verbs to describe possibility 1. must 2. cant, couldnt 3. may, might I 4. can, could 5. should, ought to 6. may not, might not E.g. He must be your brother. You two loo
3、k the same. They must be in Spain by now. They told me they were going last week. Jack must think Im crazy because I think grammar is easy! We use must in affirmative sentences when we are 100 per cent sure that something is the case. E.g. He cant be at work now for its already 11 p.m. His schoolbag
4、 is still here, so he cant have gone home. Peter cant like that show. He doesnt enjoy comedy. We use cant or couldnt when we are 100 per cent sure that something is impossible to happen. mustnt The negative form of must cant be used to describe possibility. We use mustnt to express prohibition. E.g.
5、 You mustnt smoke here. You mustnt enter that door. E.g. That may/might be a good idea. The news online may/might be false. He may/might be forgetful because of his injury in the head. We use may or might when we think something has a good possibility of being true, though we are not 100 per cent su
6、re. E.g. Such accidents can/could happen. The temperature here can/could be as high as 37. Food poisoning can/could cause death. We use can or could when we think something is true as it is often the case according to theories or habits. We also use can or could to ask for possibility. E.g. Can/Coul
7、d he be the owner of the house? Can/Could this be true? Can/Could he still be alive after all these years? E.g. They should/ought to win theyve trained hard enough. The roads should/ought to be less crowded today. He left at five in the morning. He should/ought to be home now. We use should and ough
8、t to when we expect something is true or will happen based on reasonable judgement, though we know there can be exceptions. E.g. That may/might not be a good idea. He may/might not have enough money for a new car. He may/might not be fit for the post. We use may not and might not when we think somet
9、hing is untrue or wont happen, though we are not 100 per cent sure. 1. Look at these tracks. It _ (must, may) be a wolf. Dont be so sure. I think it _ (must, might) be a fox. 2. They often go to the restaurant for meals. They _ (mustnt, cant) be very poor. 3. The book _ (must, should) belong to Tom.
10、 It has his name on it. must might cant must Exercise 1: Choose the right modal verbs according to the context. Modal verbs followed by different verb forms Modal verbs + II do (the base form) be doing (the continuous form) have done (the perfect form) 1. When we talk about possibility of something
11、at present or in the future, we use modal verbs + do (the base form). 3. When we talk about possibility of something that happened in the past, we use modal verbs + have done (the perfect form). 2. When we talk about possibility of something that is happening now, we use modal verbs + be doing (the
12、continuous form). E.g. He may come to see us tonight, but he is not sure yet. E.g. He might be listening to the radio now. E.g. Its wet outside. It must have rained last night. More examples He must know the result. He must have known the result yesterday. He started the job early in the morning. He
13、 should/ought to have finished it by now. Fred isnt home yet. He may/might have missed the train. Lets hurry up. They may/might be waiting for us. More examples They may/might not be having dinner in the restaurant now. They cant/couldnt be having dinner in the restaurant now. She may not have locke
14、d the door. Youd better go and have a look. She is always careless. She cant/couldnt have locked the door. He left in such a hurry that he might not have left us a message. He left in such a hurry that he couldnt have left us a message. More examples Can/Could she be expecting us now? Can/Could he h
15、ave received my text message? Can/Could they have gone to Boston on business? 1. He _ (have) his dinner now, for the dining hall is still closed. 2. I cant understand why our boss is late. He _ (miss) the early bus. 3. Where are you going this month? We _ (go) to Xiamen, but we are not sure. Exercis
16、e 2: Fill in the blanks with the right forms of the given words. cant be having may/might have missed might/may go must do (the base form) Modal verbs + be doing (the continuous form) have done (the perfect form) Summary Modal verbs to describe possibility 100 per cent sure cant, couldnt may, might can, could should, ought to may not, might not not 100 per cent sure
