GWD25-Q37

In 1981 children in the United States spent an average
        of slightly less than two and a half hours a week doing
        household chores; by 1997 they had spent nearly six hours a week.

A.   chores; by 1997 they had spent nearly six hours
        a week

B.   chores; by 1997 that figure had grown to nearly
        six hours a week

C.   chores, whereas nearly six hours a week were
        spent in 1997

D.   chores, compared with a figure of nearly six hours a week in 1997

E.   chores, that figure growing to nearly six hours a week in 1997

答案是B。恩，看过前面的讨论了，但是我之前选的是A。

有人说A是时态问题，但是B也是过去完成时啊~~

然后我在想是不是因为这里的children用they指代错误的原因，因为1981年的children和1997年的children是不一样的小孩，不能在1997年里用1981年的children。。。像绕口令。。。请NN解惑~~

同意你的理解

A,到1981年，他们已经花费了XXX，

逻辑意思变成，他们在一个时间花费了多少，另一个时间花费了多少，

1981年这个数字不到2.5小时，到1997年，这个数字已经增加到6个小时。

时态的问题不能光看时间标志，还需要考虑逻辑意思。

open to discuss

那么C和E的错误呢？

C是因为被动的原因么；E的话看上去就怪怪的，但是又说不出来什么地方错。

c, compared with a figure.. seems the "figure" compare" with the "children"

e, the absolute structure plays the role of adverbial modifier. Here "that firgue growing" seems an action accompanying the action in 1981. Logicaly error

sorry

c, I agree with you, the passive verb is unnecessary and inconsistent with the first part of this sentence