在这一章，我们将给很多简短的文章，每一段文章的后面，我们都会有详细的解释，相信这些解释将有助于读者对于文法的了解。
（１）
Dear Mother:
I arrived at the Taipei Train Station around one o'clock in the afternoon yesterday. My friend, Mr. Chen, greeted me in the station. We took a taxi to go directly to the university and checked into the dormitory. The dormitory is a very old one. I will live with three other boys and I met two of them already. Both of them are from Taichung and they are both quite friendly.
We went to the dormitory cafeteria for dinner. The food is not that good. Dear Mother, I miss you and especially the food you cooked for me.
Your son
这封信很简单，所叙述的事情不是用简单的现在式，就是简单的过去式，当然也有一次用了将来时。
绝大多数的句子都用了简单的过去式，因为这些句子都是叙述过去所发生的事，用现在式的有以下几句：
The dormitory is a very old one.
Both of them are from Taichung.
The food is not that good.
I miss you and the food you cooked for me.
为什么这几句话要用现在式呢？道理很简单，这几句话描写的是一些状态，而并非过去发生的事。
〝The dormitory is a very old one.〞
〝Both of them are from Taichung.〞
〝The food is not that good.〞
〝I miss you and the food you cooked for me.〞
等四个句子都是目前存在的事实，所以要用现在式。
现在我们不妨看一下冠词的情形，我们可以看到很多地方都用了the，如：
the Taipei Train Station
the afternoon
the station
the university
the dormitory cafetervia
the dormitory
the food
the food you cooked for me
各位读者一定可以注意到在the后面的名词都有所指，举例来说，the university指那所作者要去念的大学，他的妈妈知道他所说的是那一所大学。The dormitory指那间他已搬进去住的宿舍。凡是有所指的名词前面，原则上都应该加the。
哪里用了〝a〞呢？注意，我们用了两次
a taxi
a very old one
读者应该不难看出为什么这里我们不能用the，而一定要用a。
（２）
Mary: "Hello, this is Mary. Who is calling?"
John: "Hi, this is John. How are you?"
Mary: "I am doing fine. In fact, I am studying for the final examination now."
John: "Oh, I am sorry. When will the exam be over?"
Mary: "This Friday."
John: "Then, can we have dinner Friday evening?"
Mary: "OK, where are we going to eat?"
John: "How about the Chinese restaurant called Four Seasons?"
Mary: "That is all right with me. When do we meet?"
John: "How about six o'clock?"
Mary: "That's it. See you Friday evening at 6 o'clock at the Four Seasons."
这一篇短文主要的目的在于介绍所谓现在进行式。
Who is calling.
I am doing fine.
I am studying for the final examination now.
都是标准的现在进行式，事实上，也必须用现在进行式。
（３）
I have been interested in music ever since I was a small child. When I was seven years old, my mother gave me a violin as a birthday present. I have been taking violin lessons ever since.
I am so much interested in music that I finally decided to go to music school. This was a hard decision for me. I consulted with my parents. Both of them encouraged me to go ahead.
Yesterday, I was accepted by one of the best music schools in Taiwan. I am really happy about this.
这一段话中，我们开始用现在完成式，比方说第一句话就是
I have been interested in music ever since I was a small child.
为什么要用现在完成式呢？道理很简单，这句话里面有有〝ever since〞这个词，凡是有了这个词句，我们就一定要用现在完成式了。
另外一句用了现在完成进行式的句子是：
I have been taking violin lessons ever since.
读者不妨去看看第四章，就知道为什么这里要用现在完成进行式了。凡是〝自从〞某某日开始，而就一直在做的事情，就应该用现在完成式，或者现在完成进行式。
这一段文章里面，我们还用了被动语气。
I was accepted by one of the best music schools in Taiwan.
各位读者不妨注意，这被动语气的用法是很正当而且适宜的，如用主动这句话变成了
One of the best music schools accepted me.
这样反而并不太能表达原意。
（４）
Before I got into college, I had been to the United States and lived there for one year. This is why I could speak English better than average students.
As I studied as a college student, Hitler was secretly preparing for the Second World War. The war erupted finally when I was a senior. I was forced to quit school and was drafted into the army. I luckily survived the war and came back to resume my studying after the war was over. Since I had gone to the war, I was more mature than most of the other students.
Even now, I can still remember my days as a college student as well as a soldier.
这篇文章介绍了如何使用过去完成式，第一句话就用了过去完成式，因为有两件事，一件是〝进大学〞，另一件是〝去过美国〞，由于在进大学以前去美国，所以〝去美国〞就用了过去完成式。
请注意第二段的第一句：
As I studied as a college student, Hitler was secretly preparing for the Second World War.
这一次，我们用了过去进行式，因为有两件事，〝在学校念书〞是一件事，〝希特勒在准备发动第二次世界大战〞是另一件事，其中有一件可以用过去完成式。
同理，在第二段话的最后一句话中，〝曾经去打过仗〞用了过去完成式。
这段文章中，有一句话用了被动语气，读者不妨看这句话〝I was forced to quit school.〞，其实我们在这种情形之下，我们必须用被动语气，当然也可以用主动语气，不过那并不太自然。
也请读者注意这段文章的最后一句话仍一定要用现在式。
（５）
I have been interested in reading novels for a long time. Among all of the novels that I have read, I like detective novels the most. Among all detective novels, I especially like those written by Agatha Christe.
Last year, I started reading another kind of novels, namely science fictions. I found out that some science fiction writers are quite philosophical. Unfortunately, there are not too many of them.
I always have a dream that one day I will be good in writing novels. Do you think that my dreams may come true?
这段文章中，我们介绍了动名词的用法，第一句话的reading就是动名词，除此以外，我们还有两处用了动名词：started reading和good in writing。
读者也应该了解为什么第一句话要用现在完成进行式，在第二句话里面，当我们形容novels，我们也用了现在完成式。
请读者注意第一段的最后一句话，those written by Agatha Christe。在这里，written是一个过去分词用作了形容词，形容novels，我们也可以说those which were written by Agatha Christe.
顺便讲一下，Agatha Christe是一位非常著名的侦探小说作者。
也请大家注意，我们只能说interested in reading，而不能说interesting in reading。
（６）
Tomorrow, there will be a dancing party in our university. Since we are freshmen and most of us have never been to a large dancing party, we are naturally very much excited. I must say that I am not that excited. Although dancing is interesting, I often think that the music is too loud. Besides, as a bystander, I often find the way that the young people dance these days is so funny. When they dance, they often remind me of monkeys.
Well, I must admit that playing basketball is more interesting to me. But, unfortunately, I cannot play basketball tomorrow because the courts will be used for the dancing party.
这一段话主要的目的是介绍现分词和过去分词用成形容词的做法。第一个现在分词是dancing，dancing 在这里形容party。
我们在这里看到有些时候，我们应该用现在分词，有时要用过去分词。请看以下的句子：
We are naturally very much excited.
在这里，我们一定要用excited，绝对不能用
＊We are naturally very exciting.
下一句
Although dancing is interesting,
在这里，我们必须用interesting，而不能用interested。也就是说，我们不能说
＊Although dancing is interested.
（７）
We probably all believe that we should love others and forgive those who do bad things to us. Unfortunately it is often hard for us to practice what we believe in. For example, if someone really hurts us badly, we just do not know what we should do. Should we take some kind of action to hurt the person who hurt us, or should we forgive him?
The truth is that we may still seek justice. It is right if we want a criminal to go to jail for his crime. Yet, we should never have hatred in our hearts.
这篇文章的目的在介绍〝子句〞的用法，请注意这篇文章内的很多子句，举例来说
that we should love others and forgive those who do bad things.
就是一个子句，这个子句是believe的受词，有趣的是，这个子句内部又有一个子句，那就是
who do bad things to do.
这个子句是形容those的。
以下是这一段文章的全部子句：
that we should love others and forgive those
who do bad things to us
what we believe in
what we should do
that we may still seek justice
--------xushen ------补充-----------------------------------------------
It's useful for me. Thanks a million.
The following is my notes. That is saying, I should learn the following key points.
4-1 现在完成式（Present Perfect Tense）
完成式的形式是 verb to have + past participle，每一个动词，都有过去式和过去分词，以下就是一些例子：
什么情况之下要用现在完成式呢？
1. 首先假设我们有一件事，发生在过去，而一直延续到现在，就要用现在完成式，这种句子后面常有since或for。以下是这种情形的
（1）自从1963年，我一直在念英文。
I have studied English since 1963.
2.使用现在完成式的另一情况是强调已经完成的事，比方说，你说〝我已经写了那封信〞，就可以用现在完成式，或者，你说〝他已经完成了
工作〞。以下是这类的例子：
（1）我已经写了这封信。
I have already written the letter.
3.现在完成式用来表示一种经验，举例来说，〝我曾经到过美国〞、〝我曾见过李总统〞，这些都应该用现在完成式，例如：
（1） 我曾经到过美国。
I have been to America.
4.现在完成式可以用来表示一件过去常发生的事：
（1） 今年我国已有二次台风。 We have already had two typhoons so far this year.
（2） 他今年已发表了三篇论文。He has already published three papers this year.
对读者而言，最重要的是〝现在完成式〞和〝过去式〞煌烤乖谀抢铮孔钪匾牟煌谟冢坏┰诰渥又薪惨患シ⑸氖拢抑付ㄌ?
定的时间，就一定要用〝过去式〞，而不能用〝现在完成式〞。比方说，〝我曾经看过「铁达尼号」〞，可以用现在完成式，因为这句话没有
指明任何特定的时间，假如说，〝我昨天晚上去看「铁达尼号」〞，就一定用过去式，读者不妨看看以下的比较：
（a）I went to America last year.
I have been to America.
（b）I saw The Titanic last year.
I have seen The Titanic twice.
现在完成式常和since、for、already、never、ever等字一起使用，以下都是这类的例子：
（1）I have already had dinner.
（2）Since this summer began, we have already had two storms.
（3）It has not rained for a long time.
（4）I have never talked to this man before.
（5）I have never met your father.
（6）Have you ever been to America?
（7）He has already won three awards.
（8）I have stayed here since June.
Never 和 ever 也常是我们弄不清楚如何使用的字，一般说来， never 有否定的意思，ever则只有在问句中才会出现。
4-2 现在完成进行式（Present Perfect Progressive Tense）
如果有一个行动，从过去发生后，就一直延续到现在，可以用现在完成式。举例来说，以下的例子都应该用现在完成式：
（1） 自从1974年，我就在学校学英文。Since 1974, I have studied English at school.
（2） 自从我大学毕业以后，我就在这里工作。Since I graduated from college, I have worked here.
以第一句话为例，假如我们要强调我一直在练习游泳，而且没有间断，我们可以用现在完成进行式。
所谓现在完成进行式，形式如下：
verb to have + been + present participle
verb to have 是为了完成式，been 和 present participle 都是为了进行式。
以下是现在完成进行式的例子：
I have been studying English since 1974.
I have been working here since I graduated from college.
4-3 过去完成进行式（Past Perfect Progressive Tense）
过去完成式的形式如下：had + past participle
过去完成式是不能单独用的。用的时候，必须有另一个事件。也就是说，假如有两件事 A 和 B，两件事都发生在过去，但 A 发生在 B 以前，
A 应该用过去完成式，B 则用过去式。
以下是几个例子：
（1） 他到台湾以前，曾学过中文。
He had studied Chinese before he came to Taiwan.
（2） 他念大学以前，曾前工作过。
He had worked before he decided to go to college.
如果我们要强调较早发生事件的连续性，我们可以用过去完成进行式。过去完成进行式和现在进行式惟一不同的地方是 verb to have 的地方
一定要用had 。
以下是一些过去完成进行式的例子：
1. I had been watching TV before you called me.
2. I had been working hard in a company for many years before I went to college.
