Compare could (do) and could have (done): • I'm so tired. I could sleep for a week, (now) 9 I was so tired. I could have slept for a week, (past) Most often, we use could have (done) for things which were possible but did not happen: • Why did you stay at a hotel when you went to New York? You could have stayed with Barbara. (= you had the opportunity to stay with her but you didn't) • Jack fell off a ladder yesterday but he's all right. He's lucky - he could have hurt himself badly, (but he didn't hurt himself) 9 The situation was bad but it could have been worse. Sometimes could means 'would be able to...': • We could go away if we had enough money. (= we would be able to go away) 9 I don't know how you work so hard. I couldn't do it. Could have (done) = would have been able to (do): • Why didn't Liz apply for the job? She could have got it. • We could have gone away if we'd had enough money. 9 The trip was cancelled last week. Paul couldn't have gone anyway because he was ill. (= he wouldn't have been able to go) 9 You did very well to pass the exam. I'm sure I couldn't have passed it. (= I wouldn't have been able to pass it if I had taken it) Complete the sentences. Use could or could have + a suitable verb. 1 A: What shall we do this evening? ß: I don't mind. We ...QQuldqg, to the cinema. 2 A: I had a very boring evening at home yesterday. B: Why did you stay at home? You...................................................to the cinema. 3 A: There's an interesting job advertised in the paper. You..................................................for it. B: What sort of job is it? Show me the advertisement. 4 A: Did you go to the concert last night? B: No. We...............................................................but we decided not to. 5 A: Where shall we meet tomorrow? B: Well, I...............................................................to your house if you like. Read this information about Ken: Ken didn't do anything on Saturday evening. Ken was short of money last week. Ken doesn't know anything about machines. Kon'o car wao stolen on Monday. Ken was free on Monday afternoon. Ken had to work on Friday evening. Some people wanted Ken to do different things last week but they couldn't contact him. So he didn't do any of these things. You have to say whether he cotdd have done or couldn't have done them. 1 Ken's aunt wanted him to drive her to the airport on Tuesday. ...He couldn't have ^^ 2 A friend of his wanted him to go out for a meal on Friday evening. Ken........................................................................................................................................................................ 3 Another friend wanted him to play tennis on Monday afternoon. Ken........................................................................................................................................................................ 4 Jack wanted Ken to lend him £50 last week. 5 Jane wanted Ken to come to her party on Saturday evening. He......................................................................................................................................................................... 6 Ken's mother wanted him to repair her washing machine. For the past we use must have (done) and can't have (done). Study this example: George is outside his friends' house. He has rang the doorbell three times but nobody has answered. They must have gone out. (otherwise they would have answered) « The phone rang but I didn't hear it. I must have been asleep. 9 I've lost one of my gloves. I must have dropped it somewhere. 9 Jane walked past me without speaking. She can't have seen me. 9 Tom walked straight into a wall. He can't have been looking where he was going. Study the structure: I/you/he (etc.) must can't have been (asleep / at work etc.) been (doing / working etc.) done / gone / known / had etc. Couldn't have... is possible instead of can't have...: 9 She couldn't have seen me. ® Tom couldn't have been looking where he was going. Complete the sentences with a verb in the correct form. 1 I've lost one of my gloves. I must ...h^e.dropped,,, it somewhere. 2 They haven't lived here for long. They can't ...know... many people. 3 Ted isn't at work today. He must.......................................ill. 4 Ted wasn't at work last week. He must.......................................ill. 5 (The doorbell rings) I wonder who that is. It can't.......................................Mary. She's still i work at this time. 6 Carol knows a lot about films. She must.......................................to the cinema a lot. 7 Look. Jack is putting on his hat and coat. He must.......................................out. 8 I left my bike outside the house last night and this morning it isn't there any more. Somebody must.......................................it. 9 Ann was in a very difficult situation. It can't.......................................easy for her. 10 There is a man walking behind us. He has been walking behind us for the last 20 minute.' He must.......................................us. Read the situations and use the words in brackets to write sentences with must have and can' have. 1 The phone rang but I didn't hear it. (I / asleep) ..X.WUSt have been aeleep.., 2 Jane walked past me without speaking, (she / see / me) ...She can't,have seen me... 3 The jacket you bought is very good quality, (it / very expensive) 4 1 haven't seen the people next door for ages, (they / go away) 5 I can't find my umbrella. (I / leave / it in the restaurant last night) 6 Don passed the exam without studying for it. (the exam / very difficult) 7 She knew everything about our plans, (she / listen / to our conversation) 8 Fiona did the opposite of what I asked her to do. (she / understand / what I said) 9 When I woke up this morning, the light was on. (I / forget / to turn it off) 10 The lights were red but the car didn't stop, (the driver / see / the red light) 11 I was woken up in the middle of the night by the noise next door, (the neighbours / have / a party)............................................................................................................................................................ For the past we use may have (done) or might have (done): • A: I wonder why Kay didn't answer the phone. B: She may have been asleep. (= perhaps she was asleep) • A: I can't find my bag anywhere. B: You might have left it in the shop. (= perhaps you left it in the shop) » A: 1 was surprised that Sarah wasn't at the meeting. B: She might not have known about it. (= perhaps she didn't know) ® A: I wonder why Colin was in such a bad mood yesterday. B: He may not have been feeling well. (= perhaps he wasn't feeling well) Study the structure: [/yon/he (etc.) may might been (asleep / at home etc.) (not) have been (doing / waiting etc.) done / known / had / seen etc. Sometimes could has a similar meaning to may and might; a The phone's ringing. It could be Tim. (= it may/might be Tim) • You could have left your bag in the shop. (= you may/might have left it...) But couldn't (negative) is different from may not and might not. Compare: • She was too far away, so she couldn't have seen you. {- it is not possible that she saw you) a A: I wonder why she didn't say hello. B: She might not have seen you. (a perhaps she didn't see you; perhaps she did) Read the situations and make sentences from the words in brackets. Use may or might. 1 I can't find George anywhere. I wonder where he is. a (he / go / shopping) .. Hemay have a.Oneshopping,.. b (he / play / tennis) - ..He might.be.playinä.tefinis,..,. 2 I'm looking for Helen. Do you know where she is? a (she / watch / TV / in her room)................................................................................................ b (she / go / out) ......,.........................................................-............................................................... 3 I can't find my umbrella. Have you seen it? a (it / be / in the car)........................................................-...............................................■.................. b (you / leave / in the restaurant last night)...................................,.......................•••••............... 4 Why didn't Tom answer the doorbell? I'm sure he was in the house at the time. a (he / be / in the bath)...................................................................... ........................................... b (he / not / hear / the bell) ....................................................-.......................................-................ Complete the sentences using might not or couldn't, 1 A: Do you think she saw you? B: No, she was too far away. ...She oouWn/f.have.seenme,... 2 A: I wonder why she didn't say hello. Perhaps she didn'r see me. B: That's possible... She might not haveseen you,,.. 3 A: I wonder why Ann didn't come to the party. Perhaps she wasn't invited. B Yes, it's possible, She................................................................................................................... 4 A: Tom loves parties. I'm sure he would have come to the party if he'd been invited. B: I agree. He............................................................................................................................ í A: I wonder how the fire started. Do you think it was an accident? B: No, the police say it....................................... .................. -..................................................... 6 A: How did the fire start? I suppose it was an accident. B: Well, the police aren't sure. They say it................................................................................ 'You should have done something' = you didn't do it but it would have been the right thing to do: 9 ir was a great party last night. You should have come. Why didn't you? (= you didn't come but it would have been good to come) « I'm feeling sick. I shouldn't have eaten so much chocolate. (= I ate too much chocolate) » I wonder why they're so late. They should have been here an hour ago. a She shouldn't have been listening to our conversation. It was private. Compare should (do) and should have (done): s» You look tired. You should go to bed now, o You wenr to bed very lare last night. You should have gone to bed earlier. Read the situations and write sentences with should/shouldn't. Some of the sentences are past and some are present. 1 I'm feeling sick. I ate too much.....I, ahpuldn't have.eaten so much. 2 That man on the motorbike isn't wearing a helmet. That's dangerous. He ..Should.be wearing a helmet. 3 When we got ro the restaurant, there were no free tables. We hadn't reserved one We................................................... 4 The notice says that the shop is open every day from 8.30. It is 9 o'clock now but the shop " isn t open yet................................... 5 The speed limit is 30 miles an hour, but Catherine is doing 50. She.............................. 6 I went to Paris. A friend of mine lives in Paris but I didn't go to see him while I was there...... when I saw him later, he said: You......................................... 7 I was driving behind another car. Suddenly, the driver in front stopped without warning and I drove into the back of his car. It wasn't my fault......................... 8 I walked into a wall. I wasn't looking where I was going. 32.3 Read the situations and make sentences with needn't h ave. 1 George went out. He took an umbrella because he thought it was going to rain. But it didn rain. ...He needn't hayetake.n.an..umbrejla... 2 Ann bought some eggs when she went shopping. When she got home, she found that she already had plenty of eggs. She..................................................................... 3 A friend got angry with you and shouted at you. You think this was unnecessary. Later yoi say to him/her: You............................................................................. 4 Brian had no money, so he sold his car. A few days larer he won some money in a lottery. He............................................................................................ 5 When we went on holiday, we took the camera with us but we didn't use it in the end. 6 I thought I was going to miss my train so I rushed to the station. But the train was late and the end I had to wait 20 minutes. ....................................... 32.4 Write two sentences for each situation. Use needn't have in the first sentence and could have ;"; the second (as in the example). For could have see Unit 27. 1 Why did you rush? Why didn't you take your time? ...!fou. needn't.hay»; .rusheŕl..You ppuldhaye ta ken your. time,... 2 Why did you walk home? Why didn't you take a taxi? 3 Why did you stay at a hotel? Why didn't you stay with us? 4 Why did she phone me in the middle of the night? Why didn't she phone me in the E Degrees of probability in the past • For different degrees of probability in the past we use; modal verb + have + past participle. See the table below • Notice in the table that will/won't have + past participle is an assumption (you think something is true although you have no proof), for certainty in the past we just use a normal past tense like the past simple. assumption You'll have seen our new model. It's in all the shops deduction friere was no answer from her phone. She must have been in a meeting. Both the meeting rooms were empty She can't have been in a meeting. expectation They should/ough t to have arrived by now. I hope they haven't got lost. uncertainty Yes, t see what you mean now. I could have been wrong about that. We're only five minutes late. The '• 'k rn'.g■>f not have slartedyet. assumption You won't have seen our new model. It's not in the shops yet. Christmas could haut bee» an unhappy one last year if you ordered presents online. Many cuslomei were still miling for lifts to arrive long after the holidays had ended. (Industry Week website) F 'Possibility' • Be careful with the word 'possibility' because it refers to two different ideas in English: uncertainty and ability. Study these examples: uncertainty (there is a chance that something will happen) It's possible that the share price will recover. (= the share price might/could recover) ability (the mental skill or physical power to do something) It's possible for our factory to produce 800 cars a month. (= our factory can produce ...) For uncertainty see sections C and D of this unit. For ability see unit 11. • To talk about a past possibility we use could + have + past participle. I could have booked an earlier flight, but it left at 7.30 in the morning. This is an opportunity that didn't happen. To talk about a past impossibility we use couldn't + have + past participle. / couldn't have booked the earlier flight-it was completely full. Exercise S Martin and Anne have arrived at check-in at Heathrow Airport. Complete their dialogue with musí, might can't, must have, might have or can't have. Use each word once only. iriN. OH no. I "n'r nnd my passport. ANNE: YOU'ľť joking. MA»TIN: No. really, it's noc in my briefcase. Anne: Well, it (1)......KWÍÍ:......be in your other bag. Quick have a look, martin- It's not there. Where on earth is it? Míne Well. I don't know. Do you chink you (2).....................terč it at home? martin Thac's impossible. [ (3) ___...............done. I checked I had it with me four times before I lert die house. se OK, calm down. What jbouc checking your coat pockers; You never know, it (4).....................be there. MARTIN No, ic isn't.This is ridiculous. We're going to miss our night. ANSE Look, you (5) .....................be looking in the right place. CHECK-rN atte\[>ent Excuse me. ^ir. h that your passport there on the ground: MARTIN Oh. ves. so it is. Ah. ľ (6) .....................dropped it when I was looking for the rickets.