Computer
这里的if是一个条件句。后面出现的两个逗号之间的东西从位置上说是一个插入语，从成份上来说是一个同位语，是对前面的名词the smaller one进行解释。我们通常用一个名词性短语或从句来作为同位语
14. I don’t think I it’s necessary to buy the bigger one.我想没必要买较大的那个。
我们通常在think, suppose, expect, imagine等表示心理活动的动词后面不加否定含义的宾语从句。如果后面的从句使一个否定句，我们常常将从句谓语动词的否定是转移到主句的谓语动词之前。比如：
I don’t think I can get away at the moment.
I don’t suppose you need to worry.
I don’t think I know you.
15. The IBM PC 486 will be big enough for us. IBM PC 486对我们来说就够大的了。
句子中的enough可以是形容词，也可以是副词。通常我们将enough放在名词前面或形容词或副词的后面。而且通常在后面再加上不定式。比如：
I don’t have enough money to buy a house.
I am not rich enough to buy a house.
16. We mustn’t waste any more time. 我们不可以在浪费更多的时间了。
这里的情态动词mustn’t表示的不是“必须不”而是“不可以；不允许”。通常用在命令的句子中。比如：
You mustn’t talk in class. It is not a good habit.
We mustn’t go there because it is dangerous.
17. We must decide which one to buy. 我们必须决定买哪一个。
这里的which one to buy为特殊不定式短语，在句子中做decide的宾语。特殊不定式的构成形式为“关系代词或关系副词+动词不定式”。常用的关系代词有：what, which, who, whether等；常用的关系副词有how, when, where, why等。比如：
We haven’t decided what to do next.
I don’t know how to write in English.
I will ask when to start tomorrow morning.
She will ask where to live.
18. At one time, there were long queues of people waiting outside the CAAC offices. 以前，中国民航办公室前等着购票的人们排成长长的队列。
这里的waiting是一个现在分词，在句子中做people的定语，放在名词后，相当于一个定语从句。比如：
The foreigner talking with our teacher is head of the visiting group.
The man running after the bus is a friend of mine.
19. As a result, the number of people who travel by plane in China is larger than ever before. 因此，在中国乘飞机旅行的人数比以往多了。
这句话中的as a result的作用相当于一个副词，意思相当于so。比如：
He hurt himself. As a result, he couldn’t go to school.
这句话中的the number of 的中心词是number，说明谓语动词肯定是单数的。比如：
The number of the books in this bookshop is more than 200,000.
20. 我们在很多句子中都用一个代词来代替前面提到的名词，常见的有one, it和that。这三个词都是代词的时候的区别：
1, one=a/an +noun 所代表的是前面提到的同类中的任何一个
He has no book and no money to buy one.
The hat is too small. Please show me a larger one.
2, it= the/this/that/adj.+ noun 指同一件事物
He has a book, but he will not lend it to me.
I drank some iced water, but it made me more thirsty.
3, that = the + noun 指前面所提到的同一类中的另外制定的一个.
The air of the country is purer than that of the city.
比较下面三句话：
I cannot find my umbrella; I think I must buy one.
I cannot find umbrella; I don’t know where I put it.
The umbrella you bought is cheaper than that I bought.
教学设计方案Lesson 33
一、Teaching Aims
1. Help Ss understand the general ideas and some details in the dialogue
2. Practice in pairs on making a new dialogue about something they are about to buy
3. Teach them how to use some of the words and expressions in the dialogue
二、Teaching procedures
Step I Warming Up
1. Give a student 5 minutes to have his/her own free talk about anything he/she enjoys
2. Encourage Ss to ask the student questions about his/her free talk
3. Ask Ss how many of them have got a computer at home
4. Ask those who have computers what kind of computers they are using
5. Write down “486, 586, desktop, laptop, PC, Mac, Gameboy” on the blackboard
Step II Listening
1. Play tape of Lesson 33 twice and ask them to listen to the tape without looking at their books
2. Give Ss question before they listen and ask them to try to understand the dialogue with those questions
1) How many people are there in the dialogue?
2) What are they talking about?
3) Do they finally agree with each other?
3. Ask three students to answer the questions above
Step III Reading
1. Ask Ss one by one questions about the dialogue:
1) What did Jenny probably ask Mei Ge to do before they have the dialogue? (to find out the price for the IBM PC 486)
2) What does Jenny prefer to buy, PC 486 or PC 586? Why? (see book for the answer)
3) Why does Mei Ge want to buy the smaller one?
4) Why can’t they waste any more time? (price may go up and the factory needs the computers badly)
5) What is their final decision? (not mentioned)
2. Ask the next student to correct the mistakes if any
3. Give Ss one minute or two to go over the dialogue again and then ask one of the students to be Jenny and tell the others what has happened in the dialogue
One possible answer:
I am Jenny and I am working with Mei Ge in a factory. Our factory planned to buy a new computer so Mei Ge and I talked about buying a new computer. I asked Mei Ge to find out the price of the IBM PC 486 but I want to buy the IBM PC 586 because it is better and bigger. What’s more, we will change the 486 for 586 in a few years’ time. But Mei Ge still prefers the smaller one because he thinks it is a waste of money to buy a very good one. He believes PC 486 is good enough. We will meet again to make a decision the next day.
4. Ask another student to b
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