must be, can't be
Guessing about now: must, can't, might
must = I'm sure it's true; can't = I'm sure it isn't true; might or could = maybe. Then the plain verb: must be, can't be, might be.
- You must be tired.
- That can't be Chloe; she's in Spain.
- She might be at the gym.
«Debe de estar cansado» is He must be tired; «no puede ser él» is It can't be him. No to after must.
For 'I'm sure it isn't true', use can't: That can't be right. (mustn't usually means it isn't allowed; American English sometimes says must not be for a guess.)
Also on this page: might and could · must be doing · must have done (about the past)
Try 6
Six quick questions, easiest first. At the end you'll see which mistake you make.
- Ana plays tennis every morning and goes cycling at weekends. She ______ a very active person.should being · must to be · can't be · must be
- Dan did fifty press-ups without stopping, so he ______ very strong.must being · must be · can't be
- Lena has just gone to bed with a high temperature, so she ______ feeling very well.must be · can't be · can't to be
- Mia says she feels fine and has been playing tennis all afternoon, so she ______ seriously ill.can't be · must be · can't being · doesn't must be
- Tom has a high temperature and a terrible cough. He ______ ill.must be · must is · must to be · can't be
- Ana ran ten kilometres this morning and looks fresh. She ______ unfit.can't being · can't be · must be
- Their children are always playing outside, so the children ______ very active.can't be · must be · must being · must to be
- Ben has just finished a gentle walk and is laughing. He ______ in pain.can't be · can't being · must be
- Your brother eats vegetables every day and plays football three times a week. He ______ a very healthy lifestyle.must to have · must have · must has
- You have been training since six o'clock, so you ______ very tired now.must be · can't be · must to be
- That jacket ______ real leather at that price; it's cheaper than a pizza.can't to be · can't be · must be
- Everyone coming into the shop is shaking an umbrella, so it ______ outside.must raining · must be raining · can't be raining
Show the answers
- must benot can't be: must where you mean can't (or the other way round)not must to be: must to, must being, must has
- must benot can't be: must where you mean can't (or the other way round)not must being: must to, must being, must has
- can't benot must be: must where you mean can't (or the other way round)not can't to be: must to, must being, must has
- can't benot must be: must where you mean can't (or the other way round)not can't being: must to, must being, must hasnot doesn't must be: must to, must being, must has
- must benot must is: must to, must being, must hasnot can't be: must where you mean can't (or the other way round)not must to be: must to, must being, must has
- can't benot must be: must where you mean can't (or the other way round)not can't being: must to, must being, must has
- must benot can't be: must where you mean can't (or the other way round)not must being: must to, must being, must hasnot must to be: must to, must being, must has
- can't benot must be: must where you mean can't (or the other way round)not can't being: must to, must being, must has
- must havenot must has: must to, must being, must hasnot must to have: must to, must being, must has
- must benot can't be: must where you mean can't (or the other way round)not must to be: must to, must being, must has
- can't benot must be: must where you mean can't (or the other way round)not can't to be: must to, must being, must has
- must be rainingnot must raining: must to, must being, must hasnot can't be raining: must where you mean can't (or the other way round)
Common mistakes on this point
Not: She ran ten kilometres, so she must be ill.
Say: She ran ten kilometres, so she can't be ill.
must = I'm sure it's true; can't = I'm sure it isn't true.
See this mistake on its own page ›Not: You must to be tired.
Say: You must be tired.
must, can't, might + the plain verb: must be, can't be, must have a car (not must has).
See this mistake on its own page ›