2)有时that和those指前面讲到过的事物，this 和these则是指下面将要讲到的事物，例如：

I had a cold. That's why I didn't come. 

What I want to say is this ; pronunciation is very important in learning English．

3)有时为了避免重复提到的名词，常可用that或those代替，例如：

Television sets made in Beijing are just as good as those made in Shanghai．

4)this 在电话用语中代表自己，that 则代表对方。例如：

Hello! This is Mary. Is that Jack speaking?

4. 反身代词

英语中用来表示"我自己"，"你自己"，"他自己"，"我们自己"，"你们自己" 等意义的代词称为反身代词，也有人称之为自身代名词，其形式如表所示。

反身代词可以在句中作宾语，表语，同位语。

1)作宾语，表示动作的承受者就是动作的发出者，主语和宾语指同一个人或一些人。

He called himself a writer． 

Would you please express yourself in English?　

2)作表语。

It doesn't matter．I'll be myself soon．

The girl in the news is myself． 

3)作主语或宾语的同位语，表示亲自或本人。

I myself washed the clothes．（=I washed the clothes myself.）（作主语同位语）

You should ask the teacher himself．（作宾语同位语）

5. 不定代词

不是指明代替任何特定名词的代词叫做不定代词，在句中可作主语、表语、宾语和定语。现将几个常用的不定代词举例说明如下：

1)some与any的区别

①some多用于肯定句，表示“一些，几个”作形容词时，后面可以接①不可数名词+单数动词；②可数名词+复数动词。

Look! Some of the students are cleaning the library.

Some rice in the bag has been sold out.

②any多用于疑问句、条件句和否定句中，表示“一些，任何”用作形容词时，后面可以接①不可数名词+单数动词；②可数名词+复数动词。

If you have any questions, please ask me.

There isn't any orange in the bottle.

Have you got any tea?

③any和some也可以作代词用，表示“一些”。any多用于疑问句或否定句中，some多用于肯定句中。

How many people can you see in the picture?

I can't see any.

If you have no money, I'll lend you some.