1）as, when 引導短暫性動作的動詞。 Just as / Just when / When I stopped my car, a man came up to me. 2）當從句的動作發(fā)生于主句動作之前，只能用when 引導這個從句，不可用as 或 while?！ ?When you have finished your work, you may have a rest. 3）從句表示"隨時間推移"連詞能用as，不用when 或while?！ ?As the day went on, the weather got worse. 日子一天天過去，天氣越變越壞。