高一英语（人教版）必修3同步测试卷及知识点讲解资料（附讲解、部分上课ppt、答案）

一、 before用作连词 (3) 1． before用作连词时，意思是“在……之前；还没来得及 …… 就”。例如： Before I could say a word, she had rushed out of the room. 不等我说一句话，她就冲出了房间。 Don’t count your chickens before they are hatched. 不要高兴得过早。 before用法 2． 用于It + be + 时间段 + before...句型中，意思是“在……之后才……”。例如： It will be five years before I come back. 我五年后才能回来。 It was not long before the enemy was driven out of their country. 不久之后，敌人就被赶走了。 如果主句中用否定式，则表示“不多久……就”。 It won’t be long before they understand each other. 他们不久就会互相了解的。 3． 还有“趁……（还没有）”之意。 例如： They are thinking of buying the house before the prices go up. 他们正在考虑趁房价未涨时把房子买下来。 Do it before you forget it. 趁早动手，以免忘了。 二、before用作介词 before用作介词时, 可以指时间“earlier than在……之前”，也可以指位置“in front of在……之前”。例如： Several weeks had gone by before I realized it. 在我意识到之前几周已经过去了。 The scientists had tried out many kinds of chemicals before thy found the right one . 再发现最合适的化学物质之前，科学家们已经试过很多种了。 He was brought before the judge. 他被带到法官面前。 三、before用作副词 before用作副词时，意思是“at an earlier time / in the past以前”。例如： I’ve seen the film Titanic before. 我以前看过《泰坦尼克》这部电影。 I have never seen such beautiful flowers before. 我以前从未见过如此美丽的鲜花。 before long “很快，不久” 各种时态 long before “很久以前” 一般用在过去时或过去完成时 例如： ① Before long, he went to America. 不久他就去了美国。 I hope to see you before long. 我希望不久后再见到你。 ②She said she had read the novel long before. 她说她很久以前就读过这部小说。 That happened long before. 那件事发生在很久以前。 before long与long before的区别 do you know??? 一.用作介词， 意思是“从……以来， 自从”， 常与完成时连用。    　I haven‘t written home since Christmas　自圣诞节以来， 我未曾写信回家。 二.用作副词，意思是“从那时以后(一直到现在)”， “其后(到现在之间)”; ever since从那以后一直 (更加强调since的用法)。 Since 的用法 Things have not changed very much since. 从那时起， 情况并没有太大的改变。 His first book was a great success and he has been famous as a writer ever since. 他的第一本书非常畅销， 从那时起他就成了一位名作家。 He got a job with the firm in 1970 and has worked