The first use of atomic weapons was in 1945,and their power __ increased enormously ever since
问题描述：
The first use of atomic weapons was in 1945,and their power __ increased enormously ever since
这里为什么用has been 而不是用had been
答
ever since 要求句子必须用现在完成时,意思是“自从那时起一直到现在”.那又是为什么呢 为什么ever since 要求句子必须用现在完成时因为这个词组的意思决定的。你想自从那时起，一直到我们说话时截止，是不是现在完成时啊？又如：I have never met him again ever since. 自从那时起一直到现在我就一直没有见到他。