一、一次有趣的语法实验
我们曾经在一个50人的普通班级中做过一次语法实验：英语老师让学生做一个汉译英的句子，题目是：“约翰吃了一个苹果。”这本来是个十分简单的汉译英句子，属于“主+谓+宾”结构，时态也很简单，不应该有什么问题。然而，问题恰恰就出在“动词时态”上。结果出现了如下几个答案：
1. John eat an apple. （一般现在时，eat用原形）
2. John eats an apple. （一般现在时，eat加s）
3. John has eaten an apple. （现在完成时）
4. John ate an apple. （一般过去式）
5. John had eaten an apple. （过去完成时）
认为句(1)正确的学生，占2名。
认为句(2)正确的学生，占6名。
认为句(3)正确的学生，占17名。
认为句(4)正确的学生，占11名。
认为句(3)和句(4)都正确的学生，占9名。
认为句(5)正确的学生，占5名。
对于以上结果，我们感到惊讶。其实，这句话用现在完成时或者一般过去式，都是正确的，然而认为句(3)和句(4)都正确的学生，仅仅占了9名。更有甚者，认为应该使用“过去完成时”的同学，却理直气壮的说：“约翰吃了一个苹果，”不就是发生在过去的时间吗，他“吃了”不就是完成了吗，那么，为什么不用“过去完成时”？这位同学根本不明白“过去完成时”的真正含义，由此看来，语法已经到了非学不可的地步了。要想知道为什么，那么请阅读这篇文章吧。
二、动词时态的本质是什么？
时态是英语动词的一个语法概念，它跟语态、语气一样，都是通过变化动词的形式，从而达到准确表达句子语义之目的。学英语必须学好动词时态，因为时态清楚地说明了这个动词表示的动作所发生的时间(过去或现在)或者形态(进行或完成)。动词如果没有时态的话，那么，人们就无法理解一个句子所表达的准确含义了。
在中学阶段，我们必须掌握最基本的八种时态：一般现在时，现在进行时，现在完成时，一般将来时，一般过去时，过去进行时，过去完成时，过去将来时。此外，其他几种比较常用的时态，我们也应有一个大致的了解和把握。在学习过程中应特别注意以下几点：
1. 把握各种时态的特点及动词形式变化，注意易混淆时态之间的差异；
2. 准确理解语境意义，捕捉隐含的时间信息；
3. 克服惯性思维，排除“假性时间状语”的误导；
4. 注意巧变语境，培养发散性思维。
中学阶段必须掌握的8种基本时态是：
（现在时间） （过去时间）
【一般现在时】 【一般过去时】
【现在进行时】 【过去进行时】
【现在完成时】 【过去完成时】
【一般将来时】 【过去将来时】
我把动词时态划分为两大时间阵营：“过去时间”和“现在时间”，没有将来时间。凡是带有“过去”二字的时态，一律归到过去时间范畴；凡是带有“现在”二字的时态，一律归到现在时间范畴。一般将来时及其分支时态（一般将来进行时，一般将来完成时）也归到现在时间范畴，因为一般将来时及其分支时态与现在时间有着千丝万缕的联系，例如：主句与从句的时态一致问题，我们把一般将来时划到现在时间范畴；强调句中当It was...引导时，that句子使用过去时间范畴的各种时态，当It is...引导时，that句子使用现在时间范畴的各种时态或者将来时间的时态；此外，在条件和时间等状语从句中，我们用一般现在时代替一般将来时，等等。
之所以划分两大时间阵营，是为了充分反映时间和时态关系的本质。有人可能要问：“将来”不是一种时间界限吗？我认为，在现实生活中，“将来”指未来，是一种时间概念。但从语法概念理解，只有“过去”和“现在”，因为“过去”和“现在”是一道不可逾越的分水岭。而“将来”则是，从现在时间或者从过去时间向未来展望的一种时间概念。如果有人不同意我的说法，那么，我要问：“过去将来时”属于过去时间还是将来时间？
三、以write为例的八种动词时态
请读者牢记这8个句子：
1. We write a composition every week.
2. I am writing a composition now.
3. Tom has written his composition and he wants to play.
4. We will write a composition next Monday.
5. Mary wrote a composition last night.
6. He was writing a composition when I got to his house.
7. I had written my composition before the bell rang.
8. She said she would write a composition next week.
【语法讲解】
1. We write a composition every week.
【一般现在时】表示现在经常性或习惯性的动作以及事物现在的特征或状态。
【构成】动词原形。主语是第三人称单数时，谓语动词要加s，(be用am, is, are)。
【常用的时间短语】now, at present, nowadays, today, always, forever, usually, often, sometimes, at times, from time to time, seldom, never 等。
He writes a composition every week.
I am a student. He is very upset. It is fine today. They are on the playground now.
【注意】客观真理：
Light travels faster than sound.
在时间或者条件从句中，用一般时，不用将来时：
I don’t know when she will come. When she comes, please tell her the good news.
2. I am writing a composition now. Don’t trouble me.
【现在进行时】表示现在此时此刻正在进行的动作。
【构成】be (am, is, are ) + 现在分词(动词-ing)。
【常用的时间短语】now, right now, at present, today, at the moment等。
【注意】下列两句话不表示进行：
My friends are coming to our party tonight. （将来）
Mary is always coming late. （批评）
此外，有些动词表示静态意义(如“拥有，观点”等have, belong to, like, think)，不用进行时。
I have two brothers. 我有两个兄弟。
I’m having breakfast. 我正在吃早餐。
3. Tom has written his composition and he wants to play now.
【现在完成时】
(1) 表示动作发生在过去，但对现在有影响。
(2) 表示动作发生在过去，但一直延续到现在。
【构成】have (has) + 过去分词(动词-ed)。
【常用的时间短语】just, already, yet, before, for a week, for a long time, since 2008, in the past (last) three years等。
Tom has eaten something. He is not hungry now. 汤姆吃了一些东西，他现在不饿了。
His uncle has worked in this factory since he left the army. 他叔叔自从离开部队以来一直在这家工厂上班。
We’ve known each other for about two years. 我们认识大约有两年了。
How long have you waited here? 你在这儿等了多久？
【注意】在现代英语中，常用一般过去时代替现在完成时。
I saw the film already. (= I have seen the film already.) 我看过这部电影。
4. We will write a composition next Monday.
【一般将来时】表示将来要发生的动作或存在的状态。
【构成】will +原形动词 （主语是I, we时，可用shall）
【常用的时间短语】in the future, tomorrow, next week (month, year)
I will graduate from middle school next month.
She’ll be twenty years old next year.
―When will you be able to give us an answer?
―Tomorrow.
【注意】一般将来时还有其他表示法。
(1) be going to +不定式。如：
We’re going to put up a hospital here. 我们打算在这儿建一所医院。
There is going to be a lot of trouble. 这件事会有许多麻烦的。
(2) be to +不定式。如：
I’m to see off Mr. Brown this afternoon. 今天下午我要去与布朗先生告别。
When are they to hand in their plan? 他们什么时候交计划？
(3) be about to +不定式。如：
He is about to leave for
5. Mary wrote a composition last night.
【一般过去时】表示过去任何一个时间发生的，或者过去经常发生的动作或存在的状态。
【构成】动词的过去式。
【常用的时间短语】last year, in 1990, yesterday, that day。凡是已经过去了的时间都可以，包括this morning等。
I went to bed at about ten last night.
She often came to help us when she was free.
6. He was writing a composition when I got to his house.
【过去进行时】表示过去某个时间正在进行的动作。
【构成】be (was, were) + 现在分词(动词-ing)
【常用的时间短语】this time yesterday, at ten yesterday morning, at that time, at that moment, then等。
―What were you doing at this time yesterday?
―I was writing a letter to Mr. Brown.
The UFO was traveling from east to west when he saw it.
I was reading a book when someone knocked at the door.
I found a wallet on the ground when I was walking in the street.
7. I had written my composition before the bell rang.
【过去完成时】表示在过去某个时间之前发生的动作。关于“过去完成时”，有不少同学认为它是指“过去完成的动作”，这是非常错误的理解。通俗一点解释就是：两个动作都发生在过去，较早的那个动作用过去完成时，另一个用一般过去式。它的实质就是“过去的过去”。
【构成】had +过去分词(动词-ed)
【常用的时间短语】by the time…, by the end of等。例如：
The train had left by the time we got to the station.
He had learned 3000 English by the end of last term.
The children ran away because they had broken the window.
Tom was disappointed that most of the guests had left when he arrived at the party.
He told me that he had broken his glasses.
【注意】当两个动作先后分明，谁先谁后一眼就看出来时，在先的那个动作则不必用过去完成时，如：
He came in and sat down, and then took out his pen.
或者有after, before时，如：
After we said goodbye to them, we left the village. 我们向他们道别后，离开了村庄。
I heard a sudden cry just before I turned off the light. 就在我熄灯前，我听到突如其来的一声叫喊。
8. She said she would write a composition next week.
【过去将来时】表示从过去某个时间看，将要发生的事情。
【构成】would +原形动词
【常用的时间短语】the next day, the following week, in the future等。
He said that he would go to college next year.
I thought they would not come to our party if we didn’t invite them.
【注意】并非所有的would都表示过去将来时。请看：
Would you come and have tea with us?
I would like to watch T V now.
Whenever I caught cold, she would send for a doctor.
过去将来时的其他表示法。
(1) was (were) going to +原形动词：
He told us that he was going to spend his summer holidays in the countryside. 他告诉我们他打算到乡下去度暑假。
(2) was (were) to +原形动词：
I was told that my girl friend was to see me the next day. 我得知我的女朋友第二天要来看我。
(3) was (were) about to +原形动词：
As the girl was about to turn to the next customer, the old lady handed her the little package. 当姑娘就要转向下一个顾客时，老太太把小包裹递给了她。
四、关于时态的几个问题
1. 关于时态的时间范畴问题
(1) 属于现在时间范畴的时态：一般现在时，现在进行时，现在完成时，一般将来时。
这4种时态表达的概念与现在时间有关。
(2) 属于过去时间范畴的时态：一般过去时，过去进行时，过去完成时，过去将来时。
这4种时态表达的概念与过去时间有关。
2. 关于时态的呼应
如果主句谓语动词是过去时，那么从句的时态也要用过去时间的时态，这种现象叫“时态呼应”。例如：
He said he understood it. 他说他懂了。
She wasn’t sure whether you were watching TV. 她不敢肯定你是否在看电视。
He told me he had graduated from middle school two years before. 他告诉我他两年前就中学毕业了。
The boy said he would do anything for his own country. 小孩说他为自己的祖国愿做任何事。
Tom saw a girl come to him when he was sitting there. 汤姆正坐在那儿时，看见一个女孩向他走来。
当主句的谓语动词是现在时，从句的时态可以根据情况不受限制。例如：
I think I was very lucky to get that job. 我想我很幸运得到这件工作。
We wonder who built that old bridge. 我们不知道是谁建造的那座古桥。
I remember that she was crying when I got home. 我记得当我回家时她正在哭。
You will notice that this word has several meanings. 你会注意到那个单词有几种意义。
I know that she will regret for her mistake. 我知道她将为她的错误而后悔。
五、集八种时态于一篇短文
I got a letter from my sister yesterday. She lives in a foreign country. In her letter, she said that she would come to
I still remember that so many of us were living in a very small house when my sister left home. But now the new house has many large rooms and there is a lovely garden. Though it looks strange to some people, it is really very comfortable.