帮忙用was/were doing ...... when ; be about to do.....when;had just done......when造句，谢谢

They were talking when the teacher came in.老师进来的时候他们正在讲话
I was about to wash my face when he came back.
当他回来的时候我正要去洗脸
I had just finished the homework when the telephone rang.
电话铃响的时候我刚好写完了作业