问题补充:
---Your city looks beautiful. --- Yes. Lots of trees and grass last year.
A. are planted
B. have planted
C. were planting
D. were planted
答案:
A. are planted
B. have planted
C. were planting
(答案→)D. were planted
解析:句意:你们城市看来来很美丽。——是的,去年种了许多花草树木。结合语境可知下文描述的是过去某时发生的动作,故用一般过去时态。主语是动作对象,故用被动语态。选D。