---Your city looks beautiful.   

--- Yes. Lots of trees and grass _______last year.

1. A.
   are planted
2. B.
   have planted
3. C.
   were planting
4. D.
   were planted

---Your city looks beautiful.    --- Yes. Lots of trees and grass _______last year.

---Your city looks beautiful.    --- Yes. Lots of trees and grass _______last year.

A．are planted        B．have planted       C．were planting      D．were planted