19.8 比较while, when, as
 
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。
    When you have finished your work, you may have a rest.
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。





Copyright©2000-2005 万千英语族