The tower in the 1800s is the oldest building in this area.A. to be completedB. being com

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。