what were you doing at six o'clock last night?
we were washing clothes.
their teacher came in when Tom was talking with his friend.
it was raining heavily when we got home last afternoon.
when we were doing our homework at eight o'clock last evening,the telephone rang.
否定句：he wasn't watching TV at home when his father came back
疑问句：was he watching TV at home when his father came back?
yes,he was/ no he wasn't
提问：what was he doing when his father came back .
