Present and Past Speculation

MODALS and PRESENT AND PAST SPECULATION

REQUEST

POSSIBILITY

GRAMMAR

Speculating about the present

Can I go to the cinema tonight?

Lions can be dangerous.

When speculating about a present situation, we use a modal verb + infinitive. We use:

• must, to express a strong belief that something is true:

• might, may and could, when we think that it’s possible that something is true:

• can’t, to express a strong belief that something isn’t true:

Could you lend me a book?

This vase could be very valuable.

He may be waiting for us at the airport.

May I leave the room?

Would you please close the door?

John might come to your party.

Would John come with us if we asked him?

DEDUCTION - ASSUMPTION

OBLIGATION

It couldn't have been John because he's in London.

You must / have to study harder!

He drives a Ferrari. He must be rich.

I should be studying but I'm tired.

PROHIBITION

SUGGESTIONS

GRAMMAR

SPECULATING ABOUT THE PAST

You can't eat more chocolate.

You could give Mary some flowers.

When speculating about a past situation, we use a modal verb + have + a past participle verb. We use:

• must have, to express a strong belief that something happened:
• might have, may have and could have, when we think that it's possible that something happened:
• can’t have and couldn’t have, to express a strong belief that something didn’t happen:

You should never repeat what you've just said.

Shall we buy her a hat?

PERMISSIONS

ABILITY - CAPABILITY

You can go to the cinema.

I can swim.

In the evenings we could watch TV.

I could swim when I was 5.

NECESSITY

ADVICE

We must buy some more vegetables.

You should go to the doctor!