Unit 28 - Must and can’t

Question 1

For what can we use « must »?

Answer 1

• to say that you believe something is certain
  example:
  You’ve been travelling all day. You must be tired. (travelling is tiring and you’ve been travelling all day, so you must be tired.

Question 2

When and for what do we use « can’t »

Answer 2

• We use can to say that you believe something is not possible
  example:
  
  • You’ve just had lunch. You can’t be hungry already. (People are not normally hungry just after eating a meal. You’ve just eaten, so you can’t be hungry.)

Question 3

How do we use « must » and « can’t » in the past?

Answer 3

• For the past we use
  
  • Must have (done)
  • Can’t have (done)
    Example:
• There’s nobody at home. They must have gone out.
• We used to live very near the motorway.
  Did you? it must have been noisy.

Question 4

What can we use instead of can’t have?

Answer 4

• Couldn’t have
  Example:
• Sarah couldn’t have got my message