by 时间的 用法.doc

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“by＋时间”与动作性强的动词连用时，主句多用于完成式。by后的时间可指现在、过去或将来时间点。
如：By the time he was fourteen year sold，he had learned maths all by himself.
　　I shall have finished it by the time you come back.  
　　By the end of the match, they had kicked two goals and we had kicked four.
They must have finished their work by this time.
　　但是，上述情况中当时间为将来时，主句动作发生在从句动作之后时，主句动词可用一般时态。如：If you're not better by then, I'll take you to see the ，我就带你去看病。
　　Can you finish this by tomorrow? 在明天以前你能做完这件事吗？
　　间或有用进行式的。如：By the end of the first week the head of the department was saying very nice things about me. 第一周末时系主任给我多多美言了几句。
　　2、“by+时间”与表状态的动词连用多用于一般式。by后时间可为现在、过去或将来时。如：By the end of the century the population numbered about four million. 到世纪末人口已经达到四百万左右。You can borrow my camera, but I must have it back by five o'，但是五点以前一定要还我。
　　By the time that the security guards had realized what was happening, the gang were already inside the bank. 等到保卫人员明白过来发生了什么事时，那一伙强盗已经进了银