求问两道prep08中以比较为考点的sc

Julibrissin

好吧我知道比较这个点是应该早早弄清楚的但我学的不是很明白……到底什么时候该省略什么时候不该啊
以下这道题的A和C就差一个IT WAS， 为什么A就不对呢？
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.
Amaking the construction industry's economic health much more robust than five years ago  
Band make the construction industry's economic health much more robust than five years ago
Cmaking the construction industry's economic health much more robust than it was five years ago  
Dto make the construction industry's economic health much more robust than five years ago  
Ein making the construction industry's economic health much more robust than it as five years ago  
对比着197题看更弄不清了
Soaring television costs accounted for more than half the spending in the presidential campaign of 1992, a greater proportion than it was in any previous election.
A. a greater proportion than it was
B. a greater proportion than
C. a greater proportion than they have been
D. which is greater than was so
E. which is greater than it has been
这个也是比较时间状语 就选没有主谓的B 为什么？这两题的差别在哪里？