The first use of atomic weapons was in 1945.And their power increased enormously ever since.
A. is
B. was
C. has been
D. had been
网友回答
A. is
B. was
(答案→)C. has been
D. had been
解析：此题考查时态的用法。前面讲1945年首次使用原子弹，而后面一句无确定的过去时间，但ever since确定了应选C项，因为ever since和完成时态连用,指的是“从那以后”，即since 1945。