题目内容：

to make our city more beautiful
A a lot of trees have been planted B it's necessary to plant a lot of trees C a lot of trees need planting D we have planted a lot of trees

优质解答

选择D
这里主要是考察独立主格结构,前面省略了主语,应该是和后面主句的主语一样,to make的主语是人,人为了是城市更美好,所以后面的主语是人,选择D