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.
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.
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 greater proportion than it was
a greater proportion than
a greater proportion than they have been
which is greater than was so
which is greater than it has been
应该B。A中it 错,因为it 逻辑上是Soaring television costs。比的是电视花费。C时态错,应用过去时。b为省略结构,省去前面相同部分。