What were you doing when I arrived/at that time/at 8:00 last night/from 9:00 to 10:00 yesterday?
1.x09I was doing sth.When+一般过去时的时间状语从句...
2.x09How about.../ What about...
3.x09While sth./sb.was doing sth.,I was doing sth.
4.x09当不明飞行物着陆时,你正在干啥?What were you doing when the UFO landed?
5.x09当妈妈正在做饭时,我在看电视.While my mother was cooking ,I was watching TV.
6.x09I was walking down the street when a UFO landed right in front of me.
7.x09You can image how strange it was.
8.x09 I followed to see where it was going.
9.x09Isn’t that amazing!
10.x09She didn’t thinking about looking outside the station.