1、Unit 8 Natural disasters 第五课时教学案Grammar 2使用日期_ 班级_ 姓名_ 组别_ 评价_【学习目标】1. 知识目标：进一步掌握过去进行时的结构和用法。2. 技能目标：学会正确使用 when, while 和 as。【学习重点】学会正确使用 when， while 和 as。【基础引航】一、翻译短语并能会读会背。 （在文中把这些短语划出来并注明汉语。 ）1. 堆雪人 2. 拍照片 3. 跌倒 4. 做雪球 5. 躲在树后 6. 跑向他们 【要点探究】一、when、while和as都可以引导时间状语从句与过去进行时连用，表示“当时候” 。1.when:从句中的谓
2、语动词可用延续性动词，也可用短暂性动词；是延续性动词时，常用过去进行时；是短暂性动词时，常用一般过去时。从句中的动作可与主句中的动作同时发生，也可以在主句中的动作之前或之后发生。A: I was sleeping when the earthquake started. (过去点时间，强调动作的开始。)主句为延续性动作用 时态，when 从句为短暂性动作用 时态。B: When I was watching TV, my father came back . when 从句为延续性动作用 时态。主句为短暂性动作用 时态，练一练：A: 当 Peter 进来时我正在看电视。, I .B: 我在公园
3、散步时遇到了他。I (meet) him when I (take) a walk in the park.2. while: 指一个时间段。从句中的谓语动词必须是延续性动词。强调主句的动作与从句的动作同时发生或从句动作在发生的过程当中发生了主句动作。(1)从句动作在发生的过程当中发生了主句动作，此时 while=whenA: we were having supper, the light went out.B: he was riding a bike, he fell off and hurt his leg.(2)主、从句动作同时发生且都是延续性动词时，用 while，主句与从句都用进
4、行时，此时，while 译为“ 而” “一边，一边”。 （表示对比）A: My mother ( cook) while I (do)my homework.B: He was reading the newspaper I was studying.3. as: as 引导时间状语从句时，其谓语动词既可以是延续性动词，也可是短暂性动词。是延续性动词时，常用过去进行时，主句（短暂性动词）用一般过去时。此时的 as= when= while，表示“当时候” 。they were dancing, a stranger came in .请同学们注意：当主从句动作同时进行时，从句动作的时间概念淡化
5、，而主要表示主句动作发生的背景或条件时，只能用 as,表示“随着”或“一边，一边” 。A: As the time went on , the weather got worse. 。B: The little girl sang as she went. 。4.总结规律：当 When/while/as 引导的从句置于 时，用逗号将其与主句隔开。while, when and a s都表示“ ”。. while指某一段时间，从句的谓语动词必须是延续性的。A: While I was watching TV, he was listening to music. 。B: Millie was r
6、eading a book while Eddie was sleeping. 。. when和as 既可以指某一时间点，又可以指某一段时间，从句的谓语动词既可以是延续性的，又可以是瞬间性的 。 When / As he woke up, it was eight oclock. 。 指一段时间时，when、while和as都可用When/ While/ As I was waiting for a bus, I met her. 。二、完成课本 P98 练习并组内交流答案。【巩固拓展】一、用 when, while 或 as 填空。1. My mother was cooking my fa
7、ther was watching DVD last night.2. The singer waved to us she was singing the song.3. Tommy got there , the famous scientists was giving a talk on traveling.4. the famous scientists was giving a talk on traveling, Tommy got there.5. they were playing basketball, we were cheering for them.6. my uncl
8、e came to see me, I was reading.二、根据汉语提示完成句子。(翻译题方法：一找词组，二时态，三连句子注细节。)1. 昨晚 6 点我妈妈在做饭，而我爸爸在看报纸Mum was Dad newspapers at 6 p.m. last night.2. 下午当孩子们正在上课的时，地震发生了.The earthquake the children classes in the afternoon.3. 昨晚 David 正睡觉时，电话铃响了。The telephone rang David was sleeping last night.4. Tom 在骑自行车时摔倒了。Tom his bike, he .5. 她在舞台上一边唱一边跳。She she on the stage .【课堂小结】_
