问题补充:
The tower in the 1800s is the oldest building in this area.
A. to be completed
B. being completed
C. completed
D. Completing
答案:
A. to be completed
B. being completed
(答案→)C. completed
D. Completing
解析:考查非谓语动词。tower和complete是动宾关系,即“build a tower”,应该使用过去分词作后置定语,相当于定语从句which was completed in...。故选C。