when表示“当”时,怎样用?

题目

when表示“当”时,怎样用?

答案

前面的分句的谓语用 be doing sth / had done sth / be about to do sth ,when译“这时”或“这时突然”He had left the room when the telephone rang .他刚走出房间,这时电话响了.He was walking along the street...