OG11-5(黄色那本)

5. As its sales of computer products have surpassed those of measuring instruments, the company has become increasingly willing to compete for the mass market sales they would in the past have conceded to rivals.
(A) they would in the past have conceded to rivals
(B) they would have conceded previously to their rivals
(C) that in the past would have been conceded previously to rivals
(D) it previously would have conceded to rivals in the past         
(E) it would in the past have conceded to rivals (E)

这里为什么要用过去完成时, 如果根据前面的时间状语来看, 应该是过去式. 如果是把整句话看成是虚拟语气, 用have done, 不是应该至少有一个had done来做比较吗?

定语从句使用虚拟表明 “假如在过去，会如何”。 so use WOULD HAVE DONE..

pay attention, the mail clause is not 虚拟,, only the subordinate is 虚拟 to past ..