题目内容：

If the previous director had paid enough attention to the poor indoor air quality,the problem_____now.
A.would be solved
B.would have been solved
请问大家应该选哪个?理由呢?

优质解答

选B.would have been solved
这是if从句虚拟语气的固定用法.如果if从句中用的是一般过去时,主句要用would + 动词原形；如果if从句中用的是过去完成时-had + done,主句要用would + have done.这些都是一一对应的,固定用法.
意思如果已经做了----,结果会是----样,其实结果并不是这样的,表示虚拟