You ___ wear a helmet when you ride a bike. (obligation)
You must wear a helmet when you ride a bike.
You ___ smoke here. It’s forbidden.
You mustn't smoke here. It’s forbidden.
When I was younger, I ___ play the piano very well.
When I was younger, I could play the piano very well.
I ___ swim when I was 5 years old. (past ability)
I could swim when I was 5 years old.
I ___ help you tomorrow, I’m busy. (negative possibility)
I can't / won't be able to help you tomorrow, I’m busy.
You ___ have done your homework yesterday. (criticism)
You should have have done your homework yesterday.
You ___ eat so much sugar. It’s bad for you. (advice)
You shouldn't eat so much sugar. It’s bad for you.
He ___ be tired, he didn’t sleep last night.
He must be tired, he didn’t sleep last night.
She ___ be at school, but I’m not sure.
She may/might be at school, but I’m not sure.
___ I go to the bathroom? (permission)
CanI go to the bathroom? (permission)
You ___ study more.
You should study more. (should)
He ___ be at home.
He can't be at home.
Choose the correct option: She ___ be at home, her car is outside.
a) must
b) can’t
She must be at home, her car is outside.
Which is more formal?
a) Can I open the window?
b) May I open the window?
May I open the window?
In the future, people ___ travel to Mars. (possibility)
In the future, people may/ might/ could travel to Mars. (possibility)