问题补充:
Lots of trees in our city over the years. It is becoming greener and greener!
A. are planting
B. have planted
C. will be planted
D. have been planted
答案:
A. are planting
B. have planted
C. will be planted
(答案→)D. have been planted
解析:根据over the years 表示在过的几年里,一般与现在完成时态连用,又因为主语为物,是动作的承受者,故要用被动语态,故选D