until和before.docVIP

.until/not until是指：直到什么时候为止...其中非延续性动词用后者，延续性动词用前者。 例句：Not until my father came back did I fell asleep. I was awake until my father came back. 注意：倒装时倒装主句，从句语序不变。改为强调句时基本语序不变。 before在...之前，常用在时间状语从句中。 常用句型：It is +( )+before... 注意：前后时态要一致，遵从主将从现原则。 翻译：1...就...It was not long before he turned against his country.不久他就背叛了他的祖国。 2...才...It was a long time before he came to himself.很久之后他才恢复意识。 before, by, till, until (1)before指“在……之前” Please come before ten o’clock.请10点以前来。 The meeting will end after 3:00 p.m. 会议将在下午三点后结束。 表示“在……以前”时，before与by基本可通用。但by还有“截至……为止”之意，此时可与完成时连用，而before一般不与完成时连用。如： How many models have you made by the end of last month? 截至上月底你做了多少个模型？ (2)by指“不迟于，到……时为止，在……以前” I must finish my home work by lunch.午饭前我必须做完作业。 We had learned over 1000 words by the end of last term. 到上学期末为止，我们已经学了1000多个单词了。 (3)tell(until)“直到……为止” You must wait for him till tomorrow.你必须一直等到他明天。 He didn’t come back until twelve o’clock last night.他昨晚下到12点才回来。 在肯定句中，till(until)必须与延续动词连用。若与点动词连用，till(until)只能用于否定句中。列情况下宜用before不用until1.主句为肯定式，谓语为终止性动词时只用before. For example: 1). He fell asleep before I could take off his clothes. 2). We arrived there before it started to rain. 3). The holiday came to an end before I knew it. 4). He almost knocked me down before he saw me. 2.主句谓语动词强调动作的迟缓性，只用before,这时常伴有时间段状语或时间段暗示。 For example: It was quite a long time before he found the elephant.过了很长时间，他才找到大象。 We had walked a long way before we found some water.走了很长的路我们才找到水。 We had sailed for two days before we saw the land.航行了两天我们才发现陆地。 It was midnight before my brother came home.我哥哥直到半夜才回来。 3.如果强调从句谓语动作未发生就发生主句谓语动作，只用before,这时常译为“未及（不等）……就……” For example: 1）We can leave early in the morning before it gets too hot.趁天还不太热，我们上午早点离开。 2）I must write it down before I forget it.趁我还未忘，我必须把它记下来。 4.表示“与其说……倒不如……”,“与其……毋宁……”的意思时只用before. For example: I would give up my job before I agree to be dismissed.我与其被解雇还不如先辞职。 He will die of hunger before he steals.他宁愿饿死也不愿意去偷。 5