Question

How many trees ________ this year?

1. A.
   are planted
2. B.
   will plant
3. C.
   have been planted
4. D.
   planted

Answer 1

C
解析：
由句意可知此句是被动语态，故排除B、D，由时间状语this year说明用现在完成时的被动语态，故再排除掉A，所以选C。