–Tom seems not so enthusiastic as he was two years ago.

--Yes. He’s reached a point in his career_________ he has to decide what to do next.

A．that

B．when

C．where

D．which

— Mum, must I finish my homework first?

— No, you _______. [ ]

A. can't

B. mustn't

C. couldn't

D. don't have to.