楼主完全把题目理解错误了
Electric washing machines, first introduced in the
United States in 1925, significantly reduced the
amount of time spent washing a given amount of
clothes, yet the average amount of time households
spent washing clothes increased after 1925. This
increase is partially accounted for by the fact that many urban households had previously sent their clothes to professional laundries. But the average
amount of time spent washing clothes also increased
for rural households with no access to professional laundries.