must and can't: start
In this lesson
Point A of 2
must and can't: what we believe is certain
Kemi lives in a flat directly above a fish and chip shop. Her friend says: It must smell of vinegar all the time.
must here signals certainty: we have looked at the evidence and reached the only sensible conclusion.
can't signals the opposite: we are sure something is impossible.
| Subject | must / can't | Verb |
|---|---|---|
| you / she / they (etc.) | must | be (tired / hungry / at work) |
| can't | be -ing (doing / going / joking) | |
| get / know / have (etc.) |
- You've been on your feet since six this morning. You must be exhausted.
- "Gav's a brilliant cook." "Gav? You must be joking. He burns toast."
- Dylan must get lonely in that lighthouse. He sees nobody for weeks.
- You've just had a full English breakfast. You can't be hungry again.
- They only moved to Hull in March. They can't know many people yet.
Point A · Exercise 28.1 · part 1 of 3
Put in must or can't.
Example
You've been on your feet since six this morning. You must be exhausted. (must / can't)
AnswerYou've been on your feet since six this morning. You must be exhausted.That chippy be good. There's a queue down the street every Friday. (must / can't)
AnswerThat chippy must be good. There's a queue down the street every Friday.That hotel be very comfortable. Every review mentions the damp. (must / can't)
AnswerThat hotel can't be very comfortable. Every review mentions the damp.I know Carl gave me his number. I have it in my phone somewhere. (must / can't)
AnswerI know Carl gave me his number. I must have it in my phone somewhere.That woman with the spaniel walks past every morning. She live round here. (must / can't)
AnswerThat woman with the spaniel walks past every morning. She must live round here.
Point A · Exercise 28.1 · part 2 of 3
Put in must or can't.
Their flight was delayed for nine hours. That have been much fun. (must / can't)
AnswerTheir flight was delayed for nine hours. That can't have been much fun.Congratulations on the new job. You be delighted. (must / can't)
AnswerCongratulations on the new job. You must be delighted.This gas bill be right. We were away for most of the month. (must / can't)
AnswerThis gas bill can't be right. We were away for most of the month.You were only gone ten minutes. You have run all the way. (must / can't)
AnswerYou were only gone ten minutes. You must have run all the way.
Point A · Exercise 28.1 · part 3 of 3
Put in must or can't.
The Hendersons go on a cruise every spring. They be short of money. (must / can't)
AnswerThe Hendersons go on a cruise every spring. They can't be short of money.The lights are still on in Jo's office. She be working late again. (must / can't)
AnswerThe lights are still on in Jo's office. She must be working late again.
Point B of 2
must have (done) and can't have (done): the past
Tariq and Beth have come to collect their friends for the cinema. The car is not on the drive and nobody answers the door. Beth says: They must have left without us. (= nothing else explains it)
Looking back at the past, the forms are must have and can't have:
| Subject | must / can't | have | Past participle |
|---|---|---|---|
| I / you / he (etc.) | must | have | been (asleep / at work) |
| can't | have | been -ing (doing / looking) | |
| gone / got / known (etc.) |
couldn't have works in place of can't have, with no change in meaning.
- I can't find my bus pass. I must have left it on the bus. (it is the only explanation I have)
- "I grew up next to a brewery." "Did you? It must have smelt wonderful."
- Lauren hasn't replied. She can't have seen my text.
- Ryan reversed into a bollard. He can't have been looking in his mirror.
- Lauren couldn't have seen my text.
- Ryan couldn't have been looking in his mirror.
Point B · Exercise 28.2 · part 1 of 3
Complete each sentence with a verb (one or two words).
Example
I can't find my bus pass. I must have left it on the bus.
AnswerI can't find my bus pass. I must have left it on the bus.Example
Their flat is right above a nightclub. It must be very noisy.
AnswerTheir flat is right above a nightclub. It must be very noisy.You've run the village shop for thirty years. You must everybody round here.
AnswerYou've run the village shop for thirty years. You must know everybody round here.My purse isn't in my bag. I must it in the car.
AnswerMy purse isn't in my bag. I must have left it in the car."How old is Mr Patel?" "He was teaching when my mum was at school. He must at least sixty."
Answer"How old is Mr Patel?" "He was teaching when my mum was at school. He must be at least sixty."I didn't hear you come in. I must asleep.
AnswerI didn't hear you come in. I must have been asleep.
Point B · Exercise 28.2 · part 2 of 3
Complete each sentence with a verb (one or two words).
"We're off to Crete next week." "Lovely. You must forward to it." "I am."
Answer"We're off to Crete next week." "Lovely. You must be looking forward to it." "I am."Everybody knows that advert. You must it on the telly.
AnswerEverybody knows that advert. You must have seen it on the telly.There are police cars all along the bypass. There must an accident.
AnswerThere are police cars all along the bypass. There must have been an accident."Do you have a holiday home?" "You must ! I can barely pay the rent."
Answer"Do you have a holiday home?" "You must be joking! I can barely pay the rent."
Point B · Exercise 28.2 · part 3 of 3
Complete each sentence with a verb (one or two words).
Hannah is a surgeon at the Royal Infirmary, so she must a good salary.
AnswerHannah is a surgeon at the Royal Infirmary, so she must earn a good salary.
Point B · Exercise 28.3 · part 1 of 3
Use the words in brackets to write sentences with must have or can't have.
Example
We knocked at the cottage and nobody came to the door. (they / go out)
They must have gone out.
AnswerThey must have gone out.Example
Lauren hasn't replied to me. (she / see / my text)
She can't have seen my text.
AnswerShe can't have seen my text.Your new boots are beautifully made. (they / be / very expensive)
AnswerThey must have been very expensive.The curtains next door have been closed all week. (they / go away)
AnswerThey must have gone away.My scarf isn't on the hook. (I / leave / it at the pub last night)
AnswerI must have left it at the pub last night.Ewan had to sell his house when the business closed. (it / be / easy for him)
AnswerIt can't have been easy for him.
Point B · Exercise 28.3 · part 2 of 3
Use the words in brackets to write sentences with must have or can't have.
A woman stood at the bus stop for an hour without getting on a bus. (she / wait / for somebody)
AnswerShe must have been waiting for somebody.I asked the builder for a shed and he built a garage. (he / understand / what I wanted)
AnswerHe can't have understood what I wanted.When I got home, the back door was wide open. (I / forget / to shut it)
AnswerI must have forgotten to shut it.There was loud music and singing from the flat upstairs until three in the morning. (they / have / a party)
AnswerThey must have been having a party.
Point B · Exercise 28.3 · part 3 of 3
Use the words in brackets to write sentences with must have or can't have.
The cyclist rode straight across the zebra crossing in front of a child. (the cyclist / see / the child)
AnswerThe cyclist can't have seen the child.Grandad has had that suit since 1990, and it still looks brand new. (he / wear / it much)
AnswerHe can't have worn it much.
Lesson 28 · Result
How you did
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