问题补充：
The new bridge in Wenchuan last month. Now it’s easy to go to the city center.
A. built
B. was built
C. has been built
D. were built
答案：
A. built
(答案→)B. was built
C. has been built
D. were built
解析：根据时间状语last month，可知，本题所用的时态为一般过去时，同时又根据主语不能发生该动作，故用一般过去时的被动语态，其结构为主语+was或were+动词的过去分词+其他，故选B
