Question

---She must have gone back to the valley. 
---No, she______. The entrance to it was nowhere to be found.

1. A.
   mustn’t
2. B.
   needn’t
3. C.
   couldn’t
4. D.
   may not

Answer 1

C
词义辨析题。  A. mustn’t 禁止 B. needn’t 不必  C. couldn’t 不可能 D. may not 也许不 句意：她一定回到山谷了。不可能，进入山谷的路口找不到。根据语境选C