句型回顾

补充说明以下句型的用法:主句中动词was/ were doing when从句中动词过去时。这个句型可以用while引导的句子解释。如: 1)Millions of people all over the China were watching TV when the spaceship landed safely. =While millions of people all over the China were watching TV,the spaceship landed safely.飞船着陆时,全国亿万人民都在观看电视直播。