Q20

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

answer:B

B中的时态用的不对阿，我自己选的是D，请指教！

In answer D, the subject is "children", and they can not be used to compare with "hours"