when引导从句时态口诀 时间状语从句时态

时间状语从句时态  

时间状语从句的时态要根据主句决定。主句是一般将来时，从句用一般现在时。主句是祈使句，从句常用一般现在时。主句用过去时，从句也用过去的某种时态。,在复合句中，担任状语成分的从句称为状语从句。时间状语从句说明主句动作发生或进行的时间。状语从句由连词引导，其位置通常可以放在句首或句末。放在句首时，常用逗号与主句分开；放在句末时，从句前面往往不加逗号。
引导的时间状语从句的主从复合句中，动作发生在先的用过去完成时，在后的用过去时。表示前面的叙述所没有提到过的信息。它总是对所描述的事件予以引人注目的强调，意为“这时；突然”；当位于句末的分句具有引种用法时，大致有以下三种情况：,A. when 分句前面的分句使用过去进行时。如：
,He was still smiling when the door opened and his wife came in.,他正笑着的时候，门突然开了，他妻子走了进来。,I was thinking of this when I heard my name called.,我正想着这件事时，突然听到有人叫我,B. when 分句前面的分句使用 was （were） about to， was （were） on the point 等。如：
 ,We were about to start when it began to rain.,我们刚要出发就开始下雨了。,He was on the point of leaving when someone knocked at the door.,他刚要走就有人敲门。,We had hardly fallen asleep when the bell rang.,我们刚刚入睡，铃声就响了起来。,He had scarcely arrived when he had to leave again.,他刚刚到达就又要离开了。,How can I get a job when I can't even read or write？,如果我连读和写都不会，我怎么能找到,How can I help them to understand when they won't listen to me？,既然他们不愿听我的，我又怎么能帮助他们弄明白呢？,They have only three copies when we need five.,他们只有三本，而我们却需要五本。,She paid when she could have entered free.,本来可以免费入场，而她却付了款。,She stopped trying when she might have succeeded next time.,她本来下次有可能获得成功，但她却不再尝试了。,They were gossiping， when they should have been working.,他们本该工作，却在那里说别人的闲话。