Modal Verbs to Express Certainty and Possibility

We use _____ to express certainty.

• might

• must

We use _____ to express possibility.

• might

• could

• might

• all the answers

We use _____ to express certainty in the negative form.

• mustn't or mightn't

• can't or couldn't

• can't or mustn't

• couldn't or mightn't

We use _____ to express possibility in the negative form.

• may not or might not

• can't or couldn't

• mustn't or mightn't

• may not or mustn't

To express certainty or possibility about the past, we use:

• modal verb + infinitive

• modal verb + have + infinitive

• modal verb + have + past participle

• have + past participle + modal verb

She has been in over 15 films, so she _____ very well known.

• might be

• must be

You seem very familiar. Perhaps we've met before.

• We may / might / could meet before.

• We may /might / could have met before.

She _____ her glasses at home - I saw her wearing them on the bus.

• can't have left

• might not have left

Deborah is looking a bit tired. Perhaps she is working too hard.

• She may / might / could be working too hard.

• She must be working too hard.

He never goes on holiday. I don't suppose he earns much.

• He must not earn very much.

• He may not / might not earn very much.