1)as, when 引导短暂性动作的动词。 Just as / Just when / When I stopped my car, a man came up to me. 2)当从句的动作发生于主句动作之前,只能用when 引导这个从句,不可用as 或 while。来源:www.examda.com When you have finished your work, you may have a rest.来源:www.examda.com 3)从句表示"随时间推移"连词能用as,不用when 或while。 As the day went on, the weather got worse. 日子一天天过去,天气越变越坏。