They ________ learn from each other, ________ they?

1. A.
   need, needn't
2. B.
   mustn't, need
3. C.
   need, mustn't
4. D.
   must, needn't

—You _____ wash your shoes, Tom.

—But I _____ do that, Mum. They aren’t dirty.

　　A. must; needn’t

　　B. must; mustn’t

　　C. mustn’t; needn’t

　　D. need; mustn’t

They ________ learn from each other, ________ they?

[　　]

----Must trees be planted in spring?

----No, they _______

　　 A. must B. mustn’t C. needn’t D. can’t