问题补充:
The new suspension bridge by the end of last month.
A. has been designed
B. had been designed
C. was designed
D. would be designed
答案:
A. has been designed
(答案→)B. had been designed
C. was designed
D. would be designed
解析:考查时态。根据时间状语by the end of last month.到上个月末可知,用过去完成时,主语The new suspension bridge与动词design为被动关系,故选B。