Trees every year to make our city greener.
A. plant
B. are planted
C. were planted
D. will be planted
网友回答
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。