急问一个语法点

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.

1. a greater proportion than it was
2. a greater proportion than
3. a greater proportion than they have been
4. which is greater than was so
5. which is greater than it has been

语法点: 1. than 后面的 it was 或者they are 可以省略? 不能省略? 还是必须省略

2. 这里用they指代costs 还是用it 指代 proportion

这个题选什么？B吧？

要看比较的是什么东西，这个题比较的是proportion，但是比较的是the proportion in 1992和the proportion in any previous election。如果用it指代的话，指代的是the proportion in 1992，是不可能出现在any previous election的。最好的避免指代不清的办法就是省略这个it。

也有另一种表达应该是对的，a greater proportion than that in any previous election.

有的答案是A  有的答案是C  不过我选B

所以很困惑啊 ！！！