我选择的是C，但是答案是B ，这里面要如何判断呢？ 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 sixhours a week.） chores; by 1997 they had spent nearly six hours a week chores; by 1997 that figure had grown to nearly six hours a week chores, whereas nearly six hours a week were spent in 1997 chores, compared with a figure of nearly six hours a week in 1997 chores, that figure growing to nearly six hours a week in 1997