再看Prep2-67 关于比较助动词补出问题 求助！

ccergsm

67.
A pair of architects in Britain, who say that giant arches, bridges, and walls made of artificial bone could be easier to design and build than conventional structures, and already designed a number of structures, including a bridge, for showing how their idea would work.

(A) build than conventional structures, and already designed a number of structures, including a bridge, for showing

(B) build than conventional structures, and they have already designed a number of structures, which includes a bridge, to show

(C) build than conventional structures, have already designed a number of structures, including a bridge, to show

(D) also to build than conventional structures, already designed a number of structures, including a bridge, which shows

(E) to build than with conventional structures, have already designed a number of structures, including a bridge, which shows

答案C 这里比较对象是giant arches, bridges, and walls  和conventional structures
想问下这里是主语的比较么？ 如果是的话是不是要不出助动词呢？
而这里conventional structures后并没有主动词的补出是不是由于是系表结构不需要不出啊？

谢谢

ccergsm

顶一下 等待nn解答