Page 157 - Basic English Usage

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57 210
210 must: deduction

We can use must to say that we are sure about something (because it
is logically necessary).
IfA is bigger than B, and B is bigger than C, then A must be bigger
thanC.
Mary keeps crying. She must have some problem.
There's the doorbell. It must be Roger.
‘I'm in love.’ ‘That must be nice.’
In questions and negatives, we use can and can’t with this meaning, not
must and mustn't.
‘There's somebody at the door. Who ean it be?
‘it can’t be the postman. It’s only seven o'clock.’
What do you think this letter can mean?

We use must have + past participle | for deductions about the past

(can have in questions and negatives).

| must/can/can't have + past participle |

‘We went to Rome last month.’ ‘That must have been nice.’
| don't think he can have heard you. Call again.
Where can John have put the matches? He can’t have thrown them
away.

211 names and titles

We can use names and titles when we talk about people, and when we
talk to them. Therg are differences.
Talking about people

When we talk about people, we can name them in four ways.