1 . According to the new traffic rules, people ________ wear a helmet (头盔) when riding an e-bike.

A．must

B．might

C．can

D．may

2 . — Must I return this book to you right now, Millie?     
— No, you ________. You may keep it until next Friday.

A．mustn’t

B．won’t

C．needn’t

D．wouldn’t

3 . Students _______ do science experiments carefully when they are in the laboratory.

A．must

B．need

C．can

D．may

4 . You ________ put your finger into the fan, boy. It’s too dangerous.

A．should

B．mustn’t

C．needn’t

D．may

5 . —________ I wash my clothes right now, mum?
—No, you needn’t. But ________ forget to wash them.

A．Must；don’t

B．Can；do

C．Must；doesn’t

D．Can；does

6 . —Must I go out to have dinner with you, Mom?
—No, you ________, my dear. You’re free to make your own decision.

A．shouldn’t

B．mustn’t

C．needn’t

D．can’t

7 . All the visitors ________ show their ID cards, or they are not allowed to enter.

A．can

B．can’t

C．must

D．mustn’t

8 . When you take a plane, your luggage ________ weigh too much.

A．mustn’t

B．needn’t

C．shouldn’t

D．may not

9 . If a football team wants to enter the World Cup, it ________ become a member of FIFA first.

A．may

B．must

C．can

10 . —Mom, can I hang out my friends now?
—Sure, but you ________ clean up your bedroom first.

A．must

B．can’t

C．could