Past Modals for Degree of Certainty

Past Modals for Degree of Certainty

We can use past modals to talk about how sure we are that something happened.

The general form for using past modals is:

modal + have + past participle

The charts below demonstrate how to correctly use past modals.

Question:  Why didn’t Mike come to lunch with us?

If

*If there was a possible result that we know didn’t happen, we use could have.

Example: You’re lucky you didn’t get in trouble for coming late without calling. You could have been fired. (In this example, we know that the person did not get fired. It was a possible result in the past that did not happen.)

The charts below demonstrate how to correctly use past modals.

Question:  Why didn’t Mike come to lunch with us?

Okay

**Okay in British English but not common in American English

Reductions of Past Modals

When we speak, we typically reduce the past modals above. See the chart below.

Note that we never write the reduced form. The second column simply shows what the words sound like.

Multiple Choice

I’m not a fan of their logo. I think they ______ changed it years ago.

• could have

• would have

• must have

• should have

Multiple Choice

I can’t believe you met Steve Jobs in person. That _______ been amazing!

• should have

• must have

• couldn't have

• might have

Multiple Choice

Do you think we _______ avoided the economic crisis if we had taken greater precaution?

• should have

• might not have

• could have

• must have

Multiple Choice

Our new hire is exactly what we needed. We _______ asked for a better employee.

• couldn't have

• wouldn't have

• may have

• shouldn't have

Multiple Choice

John _______ been at the party last night. He’s not even in the country. He flew to Japan yesterday morning.

• couldn't have

• may not have

• might not have

• shouldn't have

Multiple Choice

The investigators have several ideas about what _______ caused the fire.

• should have

• might have

• would have

• wouldn't have

Multiple Choice

I’m not completely convinced of his innocence. I think he _______ been involved.

• must have

• should have

• might have

• must not have

Multiple Choice

You _______ mentioned it in front of the rest of the team. I would have talked to him in private about it.

• shouldn't have

• should have

• would have

• could have

Multiple Choice

Kurt ________ slept much last night. He looks awful and is on his third cappuccino.

• must not have

• must have

• could have

• wouldn't have

Multiple Choice

They said they were going to pick us up at 7 p.m. I think they _______ taken a wrong turn somewhere.

• must not have

• should have

• may have

• would have