GWD1-Q16-新问题：比较从句中时态问题

大家以前讨论的结果是B，因为A的时态不对，该用过去完成时态。但是请看下面2道题目均用的是过去时态在比较从句中，其实觉的下面2句也该用过去完成时态，但是答案都没有给过去完成时的选项！如何判定比较从句中的时态呢？似乎根据下面2句的例子，GWD的这道题目应该选A了呀（难道GWD这道和下面2道的情况不同？）

急盼牛牛指点！

大全885，Section 1，#23

23.   In 1980 the United States exported twice as much of its national output of goods as they had in 1970.

(A) twice as much of its national output of goods as they had

(B) double the amount of their national output of goods as they did

(C) twice as much of its national output of goods as it did

(D) double the amount of its national output of goods as it has（C）

(E) twice as much of their national output of goods as they had

白勇语法上的一道题目，第7章，209页，第36题。

In the 1980's the rate of increase of the minority population of the United States was nearly twice as fast as the 1970's.

a. twice as fast as

b. twice as fast as it was in

c. twice what it was in

d. two times faster than that of

e. two times greater than