Unit 8 辨析 the number of 与 a number of 的用法 现在完成时的定义、标志词-课件19张

(共19张PPT)
正确辨析
the number of 与 a number of 的用法
人教版新目标英语八年级下册Unit8
the number of 表示“...的数量”
后面+可数名词复数 / 代词，但是因为中心词是“数量”，也就是说我们的主语是“the number”,所以后面的谓语动词要用第三人称单数形式（be即is,具体因时态而定)。
the number of 表示特指问“...的数量”
The number of women in my office is 20.
a number of 表示“一些、若干”
这个词组的用法相当于some、a lot of，与some和a lot of不同的是，some和a lot of后面同时可以加可数名词复数和不可数名词；而a number of后面只可以加可数名词复数。
a number of = a lot of
A number of letters are from single parents. (许多信来自单身父母。)
如果表示数量特别多或者没有那么多，该怎么办呢？
拓展延伸
我们就可以变成a small number of 或 a large / great number of
说到这里，是不是感觉和某个词的修饰词差不多呢？
对了，这个词就是population （人口）,
China is a country of a large population. 中国是个人口大国。
a number of + 可数名词复数/代词 + 复数谓语 (一些、若干)
a number of = a lot of
the number of + 可数名词复数/代词 + 单数谓语 (...的数量)
小结：
I. 单项选择
1. The number of people in the city ______ about seven million now.
A. are B. has C. is
2. A number of visitors ______ visiting
the West Lake and the number of the
visitors ______ increasing.
A. are; is B. is; are C. are; are
课堂练习
现在完成时的定义、标志词
一、定义
现在完成时
I have been a teacher for two years.
I have lived in China since I was born.
①持续性
表示从过去开始一直持续到现在的动作或状态。
②影响性
I have already had lunch.(I am not hungry.)
我已经吃过午饭了。(现在不饿了。)
表示过去已经发生的动作对现在造成某种影响。
一、定义
现在完成时
I have read this novel twice.
I have never read this novel.
③频率性
一、定义
现在完成时
表示到目前为止动作发生的次数
持续性
二、标志词
现在完成时
①for+时间段
②since+过去的时间点，意为"自从"。
I haven't seen him since 1999.
I have studied English for six years
③since+从句（一般过去时）
Tom has taught here since he graduated.
Have you cleaned the room yet
影响性
二、标志词
现在完成时
①already，意为"已经"
We have already finished our homework.
②just,意为"刚刚"
I have just had breakfast.
③yet,意为"还″(用于疑问句和否定句)
They haven't decided yet.
Mary has read the book twice。
现在完成时
二、标志词
频率性
① ever,意为“曾经”
②never,意为"从来没有"
③twice,many times等
Have you ever cooked at home？
I have never seen such a good film.
经典例题
1.Lily is my classmate. We each other since she
came to our school.
A. know B. knew C. have known D. will know
解题思路
题目中标志词为_______，考查 ( 现在完成时/一般过去时) , 故选_______.
since
C
___________
经典例题
2.I the film yet.
A. have seen B. haven't seen
C. didn't see D. won't see
解题思路
①题目中标志词为______,考查 ( 一般过去时/
现在完成时) , 故排除______；
②yet通常用于______句和______ 句中,故题目中句子
应为(肯定句/否定句) ,意为:我还没有看过这部电影，故选___
yet
___________
C 、D
否定句
疑问句
_______
B
经典例题
3. Ice Age is a very nice film and I ______it twice.
A. will see B. see
C. would see D. have seen
解题思路
题意表明:冰河世纪2是一部很好的电影,我(到目前为止)看了两次了。题目中标志词为______,
考查(现在完成时/ 一般将来时) , 故选______。
twice
___________
D
经典例题
4 Miss Brown, we ______ cleaning our classroom. Can we go home now
A. finish B. has finished
C. are finishing D. have finished
解题思路
题意表明:布朗老师,我们打扫完教室了。现在可以回家了吗 题中无明显标志词，但强调"打扫完教室"对现在造成的____ ，故用(现在进行时/现在完成时)，故排除____, 且we后用（have/has）故选____。
影响
___________
A C
____
D
总结
一、定义
持续性
影响性
频率性
二、标志词
for,since,already,just,yet,ever,never,twice...
表示到目前为止动作发生的次数
表示过去已经发生的动作对现在造成某种影响。
表示从过去开始一直持续到现在的动作或状态。
Thank you!