He couldn't have been so rude.
You should be more attentive.
You may have the book if you want it.
Could I ask you for a glass of wate? / Could I have a glass of water?
Can I help you?
You should try some of these cakes. They are delicious.
You must drink water to live.
You shouldn't learn it by heart.
You mustn't say that again.
I can't find my pen. I must have left it at home.
He will not do anything.
