题目内容：

That teaching building_in the 1987 was the best at that time
A to be completed
B having been comlieted
C being completed
D completed
选D

优质解答

选D 是 which was completed 省略.
因为有具体时间1987,所以用过去时的被动态
A 是将被修建完
B 已经被建成
C 是正在建