have you got ready to go out, mum? 妈妈， 你为出去做好准备了吗？
21 he offers to help me with my maths. 他主动提出帮我学数学。
过去进行时 ：be (was / were + ving)
1 过去某个具体的时间：at 7 yesterday, this time yesterday, from 7 to 9 ……
my mother was cooking dinner at 6 pm yesterday.
what were you doing this time yesterday?
2由 while 引导在过去时间里同时进行的两个动作
my mother was cooking dinner while my father was watching tv.
3 由when引导的过去进行时 (注意：持续性动词和短暂性动词)
i was listening to the music when the alarm went off.
the students were playing noisily when the teacher came in.