Question

Trees ________ every year to make our city greener．

A. plant
B. are planted
C. were planted
D. will be planted

Answer 1

答案B
被动语态的用法。根据句意“每年种很多树来使我们的城市更绿”，可知用被动语态，时间状语为every year，因此用一般现在时。故选B。