关于比较的几个问题,谢谢

以下是引用fern在2004-1-28 23:36:00的发言：
987-10.A large rise in the number of housing starts in the coming year should boost new construction dollars by several billion dollars, making the construction industry’s economic health much more robust than five years ago.
(A) making the construction industry’s economic health much more robust than five years ago
  (C) making the construction industry’s economic health much more robust than it was five years ago
为什么IT WAS 不可以省略?
*比较对象对等原则

OG149. Last year, land values in most parts of the pinelands rose almost so fast, and in some parts even faster than what they did outside the pinelands.
(A) so fast, and in some parts even faster than what they did
(B) so fast, and in some parts even faster than, those
(C) as fast, and in some parts even faster than, those
(D) as fast as, and in some parts even faster than, those
(E) as fast as, and in some parts even faster than what they did
这里比较结构应该是land values in A rose as fast as, and even faster than land values outside the pineland rose. THOSE 代替 land values, 我觉得还要加个DID在THOSE前面比较才完整啊
*大概是因为要选较优的,而不是最优的

OG.150In the mid-1960’s a newly installed radar warning system mistook the rising of the moon as a massive missile attack by the Soviets.
(A) rising of the moon as a massive missile attack by the Soviets
(B) rising of the moon for a massive Soviet missile attack
(C) moon rising to a massive missile attack by the Soviets
(D) moon as it was rising for a massive Soviet missile attack
(E) rise of the moon as a massive Soviet missile attack
这题把RISING和MISSILE 相比较,虽然都是名词,可是一个表示一种动作一个是物体,这样比较对象对等吗?
*应该是rising 和attack比较吧？

Like A, B does sth.和As A does, B does sth 在表达意义上有什么区别吗, 我觉得后者更强调动作的相似性,可是在做题是,我经常分不清题目到底是要强调物体间的相似性还是动作的相似性.该怎么区分呢

谢谢
＊这个我还没注意到：P