请教PREP1-36，谢谢

prep 1-36

Thomas Eakins's powerful style and his choices of subject--the advances in modern surgery, the discipline of sport, the strains of individuals in tension with society or even with themselves--was as disturbing to his own time as it is compelling for ours. 

(A) was as disturbing to his own time as it is

(B) were as disturbing to his own time as they are

(C) has been as disturbing in his own time as they are

(D) had been as disturbing in his own time as it was

(E) have been as disturbing in his own time as

answer: B

不明白为什么要补出they，还有E选项，笔记上说as compelling for ours不是句子，比较对象不对等，什么意思呢？谢谢

其实本题主要是要表现过去和现在的对比，补出they are既保证了句子的对称性，而且恰如其分的表现了过去和现在的对比

如果不补出，省略的就是they were,显然这不是本题的作者意愿，而且也没有任何指定要用过去式的词