Mary ------her lessons from seven to ten last night .我觉得是was doing,但是答案是has been doing.
问题描述：
Mary ------her lessons from seven to ten last night .我觉得是was doing,但是答案是has been doing.
答
from seven to ten应该是时间段(相当于for long 之类的),用完成进行时更好些
was doing是用在时间点上,比如昨晚8点（at eight o'clock yesterday)正在做什么