Grammar Practice in Context - David Bolton, Noel Goodey 1997
29 May (have), might (have), could (have)
Quick reference
• We use may, might or could when we say that something is possible (in the present or the future). It may/might/could rain this afternoon.
• We use the negative forms may not/might not to talk about possibility, but not couldn’t.
I may not/might not see you tomorrow. (not I couldn’t see you tomorrow.)
• Couldn't means something is impossible.
He couldn’t be American. He’s got a British passport.
• We often use a continuous form: may be, might be, could be + -ing to talk about a present possibility. She may be lying. They could be waiting for us to ring.
• We can use either may have, might have or could have + a past participle to say that something was possible in the past.
Where is she? - She might have gone to town already. She could have left early.
• Could have can also mean that something was possible but didn’t happen.
The police could have caught him. (= They didn’t catch him.)
• Note the negative forms may not haue/might not have.
I may not have remembered to lock the door. (= It’s possible I didn’t remember.)
• Couldn’t have means that something was totally impossible.
He couldn’t have passed the exam. He never did any work. (= It wasn’t possible.)
• We often use the continuous form may have been, might have been, could have been + -ing to talk about a past possibility.
He didn't answer the phone. He might have been having a bath.
1 Complete this weather forecast, using may/might/could or may not/might not/couldn’t.
All parts of the country will have rain tomorrow but the rain (1) ... reach the south till the evening. It will be quite warm. Temperatures (2) ... reach 25°. Winds will increase from the west and (3) ... reach speeds of 45 mph on the coast but they (4) ... be as strong inland. And the forecast for the weekend? It (5) ... be better really. Dry, warm and sunny for both Saturday and Sunday.
2 This mem is in hospital. Complete what his friends are saying about him, using each of these verb forms.
couldn't
may have
may not
could
may
might have
’He (1) ... be in hospital for weeks.’
’He (2) ... recover completely.’
’But it (3) ... be worse. He (4) ... been killed.’
’This is a very good hospital. He (5) ... get better medical
treatment anywhere else.’
’The other car was on the wrong side of the road. The driver (6) ... been drunk.’
3 Helen Goodman was driving to an important meeting when her car broke down. Now she is phoning her office. Some of the lines are correct and some have a mistake. If a line is correct put a tick (✓) after it. If a line has a mistake in it, underline the mistake and write the correction in the brackets.
1 My car’s broken down. I couldn’t get to the meeting on time.
2 I mightn’t have contacted you earlier because I couldn’t find a phone.
3 I may be as much as an hour late.
4 I might have left home earlier.
5 But I may not have known that my car was going to break down.
6 This delay wouldn’t have happened at a worse time.
7 I may have to wait for hours for someone to come and repair the car.
8 I might leave my car here and take a taxi.
(...)
(...)
(...) .......
4 An office building is on fire. Two firefighters are discussing the situation. Complete the dialogue using each of these verb forms.
couldn't
might have
may not
couldn't have
may
could
’We (1) ... have got everybody out of the building. There (2) ... be more people trapped inside. But they (3) ... still be alive in there. The heat’s too intense.’ ’We (4) ... got here sooner. We came as soon as we (5) ...’ ’I wonder what started the fire.’
’It (6) ... been a gas leak. I smelt gas when we first arrived.’
5 On 15 May 1979 David Booth of Cincinnati dreamed that he saw a three-engined American Airlines plane crashing. He had the same dream for seven nights. On 22 May he told aviation officials in Washington about it. They interviewed him and wrote down the details of his dream but did nothing more. On 25 May American Airlines flight 191, a DC 10 with three engines, crashed shortly after take-off at O’Hare Airport, Chicago, killing 273 people.
Which of the alternatives are correct? (One, two or three alternatives may be correct.)
1 Booth a) may have b) could have c) might have had powers to see into the future. ...
2 He a) couldn’t have b) might not have c) may not have lied about his dreams after the crash, because the interview was recorded. ...
3 The dream a) may not have b) couldn't have c) might not have been clearer and he had the same dream seven times. ...
4 He a) couldn’t have done anything b) may not have done anything c) could have done nothing about his dreams but in fact he contacted Washington. ...
5 American Airlines a) couldn’t have b) mightn't have c) may not have grounded all its planes. ...
6 The plane a) might not have b) couldn’t have c) may not have crashed il Booth hadn’t had his dream. ...