Modal verbs exercises with answers

I failed the test. I should have studied harder.
Tom watches all the Liverpool games. He must be one of their biggest fans.
You shouldn't have told Mark. You knew it was a secret.
- Could Tom have been at home yesterday?
- She could have been. I really don't know.
They built this temple 3,000 years ago. This must have been a great civilization.
Bring your umbrella. It might rain later.
Where are we supposed to go for the test tomorrow?
Tom has got to clean up his room. It's a mess.
- Will your plane we late this afternoon?
- It may be. The airport was closed this morning.
Children under five years old must not swim without an adult.
- Wasn't that Chris in class?
- It couldn't. Chris left last week.
Tom was supposed to call Susan yesterday but he forgot.