ＧＷＤ题

Q16:

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.   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

这题怎么答案Ｃ？和先前的竞选比较不是应该用过去完成时，怎么可以用现在时态？我用排除法选了Ｂ

應該是B。

C的動詞時態應該用過去式才對。