вживання must/mustn't , should/shouldn't

Children ... spend a lot of time at the computer.

We ... keep our planet clean.

You ... clean your teeth every day.

Brian looks tired. He ... work so hard.

You ... lie to your parents or your friends.

People ... eat a lot of fruit to be healthy.

People ... cut down trees.

You ... do your homework in time.

Teenagers ... smoke or drink alcohol.

Tom has had earache for two weeks! He ... see a doctor.

You ... eat too many sweets and drink too much coffee.