问题补充：
—What were you doing at this time yesterday?
—We in the classroom.
A. read
B. were reading
C. are reading
D. was reading
答案：
A. read
(答案→)B. were reading
C. are reading
D. was reading
解析：句意：---昨天这个时候你在干什么？---我们正在教室里读书。问句问的是昨天这个时候你在干什么，应该用过去进行时，又因为主语是we,故选B。
考点: 考查时态的用法。
