The first use of atomic weapons was in 1945, and their power________ increased enormously ever since

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

答案及解析： C

解析：

思路

分析：本题考查动词时态。ever since从那以后，指从1945年以后到现在，所以句子要用现在完成时态。句意：第一次使用原子弹是在1945年，从那时到现在，原子弹的威力有了巨大的增强。