Modal verbs "must", "mustn't", "have to" or "don't have to"

I can stay in bed tomorrow morning because I ... work.

Whatever you do, you ... touch that switch. It's very dangerous.

You ... forget what I told you. It's very important.

We ... leave yet. We've got plenty of time.

Ann is feeling ill. She ... leave the party earlier.

I ... go to the bank to get some money. There is no cash on me.

The windows are very dirty. I ... clean them as I hate the mess.

These cakes are very nice. You ... have one.

We ... take an umbrella. It's not going to rain.

This is a secret. You ... tell anybody.

You ... buy a newspaper. You can have mine.

The rivers are dirty. You ... ....pollute them.