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课件网) Unit 12 Life is full of the unexpected. cream workday pie show up bean market by the end of n. 奶油；乳脂 n. 工作日 n. 果馅饼；果馅派 赶到；露面 n. 豆；豆荚 n. 市场；集市 在（某时间点）以前 Words Review Look at the following pictures and talk about what you usually do in the morning. I am waken up by the clock. Then, I stay sleepy for a while. Finally, I decide to get up ! Then, I brush my teeth, still sleepy. Next, I have breakfast, feeling better. I take my schoolbag and leave home. I come to the bus station and wait for the school bus. In the end, I arrive at school and start the whole day’s classes. Grammar Focus When I got to school, I realized that I had left my backpack at home. By the time I got to school, the bell had rung. Before I got to the bus stop, the bus had already left. I was about to go up to my office when I decided to get a coffee first. As I was waiting in line with the other office workers, I heard a loud sound. 一、概念 过去完成时表示一个动作或状态在过去某一 时间或动作之前已经完成或结束，也可能是 早已完成或结束，即“过去的过去”；也可以 指过去的动作延续到过去的某个时刻。 二、结构 “had +动词的过去分词” 三、用法 表示过去某一时间或动作之前已经发生或完 成的动作或存在的状态。句中常用by, before, when, until等词引导时间状语。 它是以过去某一时间为起点，所以过去完成 时是一个相对的时态，表示的是“过去的过 去”。只有和过去某时间或某动作相比较时 才能用到它。 例: Most of the guests had left when he arrived at the party. 当他到达晚会时，他发现大多数客人已经 离开了。 2. 过去完成时还可表示过去某一时刻之前发生 的动作或状态持续到过去某个时间或持续下去， 常与for, since等词连用。 例： When Jack arrived, Mary had been away for almost an hour. 当杰克到时，玛丽已经离开快一个小时了。 【实战演练】 用所给词的适当形式填空。 1. When I got there the bus _____ (go). 2. By the time I got to class, the teacher _____ (start) teaching. 3. We _____ (learn) over 1,000 words by the end of last term. 4. I _____ (clean) the room before he arrived here. had gone had started had learnt had cleaned by the time 的用法 by the time 意为“到……时候(为止)”，是一 个介词短语，在句中常起到连词的作用， 引导时间状语从句。 如果从句中的谓语动词是一般过去式，那么主句的谓语动词通常用过去完成时，表示“截止到从句动作发生时，主句动作已经完成，即过去的过去”。 例：By the time you came back, I had finished this book. 你回来时我已经把这本书看完了。 （从句谓语动词came back 为一般过去 时，所以主句动作用过去完成时had finished, 表示过去的过去。） 2. 如果从句中的谓语动词为一般现在时或现在完成时，那么主句中的谓语动词常用将来完成时，表示“截止到将来的某一时刻为止，主句动作将已完成。” 例：By the time I get home, they will have left. 我到家时他们将已经离开。 By the time I graduate next year, I will have lived here for five years. 到明年毕 业时，我将已经在这待了五年了。 （1） by the end of +时间点意为“到……结束时” ① +过去的时间点，主句用过去完成时； 例：By the end of last year, I had stayed in Xi’an for seven years. 到 ... ...
