21. This is ________ public place for us to do some reading. Don’t talk or laugh loudly
in _____ public.
A. a; a B. the; a C. a; / D. /; /
22. — Mum, can I help you with the cleaning?
— Thank you, dear. But you are ______ now. You must wait till you are ______
A. too young; too old B. too young; enough old
C. so young; enough old D. too young; old enough
23. — Must I return the book this week?
— No, you ______ . You can keep it for 20 days.
A. mustn’t B. needn’t C. can’t D. wouldn’t
