catch sb.doing sth.作“碰(遇)上某人正在做某事”解。例如：

　　The policeman caught two men fighting in the street.警察碰见两个人在街上打架。

　　The man was caught stealing the apples.那人偷苹果时，被当场发现。

　　be (get) caught in sth.“遇上……而受阻”之意。例如：

　　I got caught in the traffic.我因交通堵塞而受阻。

　　I was caught in a storm on my way to school.我在去学校的路上遇到了暴雨。