Modals

Basic rule

"Can", "may" and "must" are used in the present tense. But "may" is only used in questions. In the other tenses you usually use "(to) be able to", "(to) be allowed to" and "(to) have to".

Deeper explanation

Present	Past	Future
Can	was/were able to / could	will be able to
May	was/were allowed to	will be allowed to
Must	had to	will have to

If you use these forms in the past or in the future, you'd have to change the the tense of the verb (like you see in the table). In the past you usually use simple past and in the future the will-future. For "was/were able to" .You'd use "could" if the sentences is negativ or if you realised something. These forms can also be used in the present tense.

Examples

Present

Can: I can go camping if I want to.
May: May I go to the party on saturday?
Must: I Must clean my room today.

Past

Can: I was able to/You were able to go camping.
May: I was allowed to/You were allowed to go to the party on saturday.
Must: I had to clean my room yesterday.

Future

Can: I will be able to go camping.
May: I will be allowed to go to the Party on saturday.
Must: I will have to clean my room.

Exercises

Task 1:

Fill in the forms in the present tense. 1.