如果两个动词都是谓语动词，而且是并列关系，那么它们都要加ing。例如。We are singing and dancing at the party。我们正在派对上又唱又跳。表示两个动作同时进行的用法例句。1、While you were writing letters，I was reading a book。你写信的时候，在看书。2、While we were having breakfast，John was talking on the tele-phone。我们吃早饭的时候，约翰在打电话。