Trees every year to make our city greener.A. plantB. are plantedC. were plantedD. will be

问题补充：

Trees every year to make our city greener.

A. plant

B. are planted

C. were planted

D. will be planted

答案：

A. plant

(答案→)B. are planted

C. were planted

D. will be planted

解析：本题的含义是每年我们要栽许多的树，本题表示的是一般的情况用一般现在时，主语树为动作的承受者，故本题使用一般现在时的被动句，结构为be+过去分词，本题的主语是复数，故本题选B。