sb was doing sth when sth +动词过去式是什么时态

sb was doing sth when sth +动词过去式是什么时态 sb was doing sth when sb doing sth,sb doing sth 这个句型可不可以? when sb.do sth.还是 when sb.doing sth. 什么时候when sb do sth 可变成when doing sth when while and see sb doing sth 有没有 动词+sb not doing sth. have been doing sth是什么时态? Make sb.adj doing sth是什么结构 pay sb.for doing sth.是什么 意思? see sb.doing sth. sb in doing sth