求解GWD TN24-17的20，23~

20.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~想问一下B选项为什么用过去完成时？还有C选项错在哪里？

A.      that since sales of up to one-fourth of its stores
            are poor, they will be closed.

B.       it is closing up to one-fourth of its stores, which
            accounted for its poor sales

C.      it was closing up to one fourth of its stores
            because of poor sales.

D.      to be closing, on account of poor sales, up to one-fourth of its stores.

E.       having poor sales, such that up to one-fourth of its stores will be closed.

答案是C~想问一下C选项announced后面为什么不用加that就可以直接跟句子？

多谢大家~

up~