问题补充:
To solve the traffic problem, more and more bridges across the river every year.
A. were built
B. will build
C. are built
D. are building
答案:
A. were built
(答案→)B. will build
C. are built
D. are building
解析:句意:为了解决交通问题,每年河上建上了越来越多的桥。每年桥是被建造的,所以要用一般现在时态的被动语态。故选B。