Question

She hasn't written to her parents ________．

1. A.
   last month
2. B.
   for last month
3. C.
   since last month
4. D.
   in last month

Answer 1

C
现在完成时中，应用for和since短语，for+一段时间，since+具体的过去时间或一般过去时的句子，故选C。