15. --- Do you still remember when we went to Nanjing ?　　　

--- I can’t remember now but _________ sometime last summer?

A. might it be　　　　　　　　　　 　　　　 B. could it be　

C. could it have been　　　　　　　 　　　　 D. should it have been　

14. The new building will be built _________ was a wasteland 30 years ago.

A. in which　　 　　 B. where　　　　　 　 C. in what　 　　　 D. there

13. --- Look! Everything here is under construction.

　--- Oh, has the building once _________ for exhibition been pulled down, too?

A. being built B. been built　　　 　　 C. to be built　 　 　 D. built