Modals of deduction and speculation

Do you remember my birthday party last year? You _____ remember! It was the same day as your graduation.

• can't

• could

• must

Come in and sit down. You _____ be tired after the journey.

• must

• might

• can't

The exam results will be out soon. It _____ be this week or possibly next week.

• must

• might

• can't

She always gets such good grades at school. She _____ work very hard.

• must

• could

• can't

The doctor said my headaches _____ be because of the hot weather but they're going to do some tests to be sure.

• must

• could

• can't

He _____ be our teacher! He looks about twelve

• must

• might

• can't

Take this umbrella just in case. It looks as if it _____ rain

• must

• might

• can't

Why were there no buses yesterday? Maybe it was the snow or they _____ been on strike.

• must have

• might have

• couldn't have

You _____ seen her, surely! She was standing right in front of you.

• must have

• might have

• can't have

Let's ask at reception to see if they have your keys. Someone _____ found them.

• must have

• might have

• can't have