Original link : https://www.zhihu.com/question/19721822
In English grammar, what is the difference between the simple past tense and the present perfect tense?
English Private Class
https://zhuanlan.zhihu.com/PrivateClass?topic=%E8%8B%B1%E8%AF%AD%E8%AF%AD%E6%B3%95Wrote
an article on English tenses , published in the column . It should be very helpful for friends who are confused about tenses.
The pain of many people learning English from beginning to end is the tense of the sentence.
Teachers in schools always tell us the concept of different tenses directly, and then say, "This is the simple past tense and the present perfect tense, and the exam will definitely take it."
So we never seem to really figure out the relationship between tenses and verb conjugations.
Because the teacher always seems to only tell us the "what" and ignore the "why".
This article explores the relationship between tenses and predicate verbs from the most basic "why".
It splits the traditional "tense" into two parts. From the "state" and "time" of verbs, you can deeply understand the essence of English tenses. After reading it, you will suddenly be enlightened.
The structure of the article is set to:
Section 1: Differences in tense between Chinese and English
Section 2: The 5 "States" of Verbs
Section 3: The 4 "Times" of Non-Predicate Verbs
Section 4: Further Understanding of 16 Tenses
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Section 1: Differences in tense between Chinese and English
In Chinese, tenses are represented by time adverbs, while in English, they are represented by predicate verbs.
Chinese: "I ran yesterday", "I ran", "I ran tomorrow". We learn about tenses through time adverbs, and there is no change in the verb "run" in the three sentences.
English: "I ran yesterday", "I run", "I will run tomorrow". Even if there is no time adverbial in English, you can clearly see whether the background time is yesterday, now or in the future through the predicate verb.
So we can conclude:
English uses predicate verbs to reflect the time and state of actions. (please recite ten times)
Two important properties of the predicate verb are implied here:
1. The "state" of the action, that is, the "state". That is, it indicates whether it is "running", "running" or "continuing to run".
2. The "time" of the action, that is, the "time". That is to say, "I am running now", "I have finished running in the past" or "I have continued to run in the past".
This is one of the essential differences between English and Chinese. In our native language, time is not represented by predicate verbs, so this is the fundamental reason why we find "tense" difficult.
Section 2: The 5 "States" of Verbs
Take the verb write as an example
The write we see in the dictionary is its base form
At this time, the verb prototype write only expresses the concept of "writing", but it has neither the meaning of "state" nor "time".
Then in order to make it inflected as a predicate verb with tense concept, we need to give it two clothes.
The first piece of clothing is "state", as shown below:
The above picture is the five "states" of verbs, indicating the "states" of actions:
1. Indeterminate state: "Want to write, but haven't written yet", showing an uncertain state. For example, "I want to write" indicates a willingness, but the action of "writing" does not happen.
2. Progressive state: "Writing", emphasizing that the action of "writing" is taking place, which seems to be understood as the next step of the indefinite state "to write", that is, the development from "to write, but not to write" to "to write" . Emphasizing "being" is not the norm.
3. Perfect state: "Complete", emphasizing that the action of "writing" has been completed, emphasizing "completed". Again, this seems to be understood as the next step in the progressive state "writing", that is, "writing" develops into "finished".
4. Normal state: "Write often", emphasizing that the action "writing" is a normal state. It can be understood as all of 1, 2, and 3, and it is a frequent action. For example, "I write a lot" shows that I often write, which is the norm.
5. Progressive state of completion: "It has been completed, but it will continue", which can be understood as a combination of 3 and 4. For example, the publication of my [English Private Lessons] series of articles, this article has been completed, but the follow-up articles will be shared with you one after another, and this action will continue. This is an example of the completion state.
动词原形（base form）穿完第一层「态」的衣服之后，就赋予了动作不同的「状态」，这是动词原形的五种非谓语动词。动词「write」可以有「正在写」，「写完了」等不同的「状态」，这比原形「write」本身已经丰富很多，可这五种非谓语动词虽表明了动作的「状态」，但是依然没有「时间」的意义，比如「进行式writing」，虽然我们可以了解「写」的动作「正在发生」，但是我们并不能知道是「过去正在发生」，还是「现在正在发生」，或是「将来正在发生」。要赋予非谓语动词「时间」的意义，我们就要给它穿上第二层衣服，使其变成真正的谓语动词。
Section 3: 非谓语动词的4个「时」
自然而然，我们将时间轴分为三个部分，即「过去」，「现在」和「将来」。英语中还有一种可能，就是站在过去的某个时间点去预测将来，即「过去将来时」。比如我三年前预计我五年后一定会有八块腹肌，再比如上周有人预测未来五年房价一定会涨，这都是过去谈论将来的例子，也就是下图所标示的情景，从过去预测将来，即「过去将来时」。
那么这4个「时间」和5个「状态」排列组合，就自然而然的形成了英语中的16个时态，如下图：
【 注：由于「不定式」不能变换成普通意义上的谓语动词，所以这里省略去】
刚才说过，谓语动词有「时间 」和「状态」两个属性，结构上也由「时间＋动作状态」构成。 上图中「+」之前的 助动词突出了动作的「时间」，「+」之后的非谓语动词则突出了动作的 「状态」。
将上图总结成表格：
注：表格中的「助动词」突出「时间」，「主动词」突出动作「状态」。
自此，动词原形（base form）通过两次变形，第一次具有了「动作状态」属性，第二次具有了「时间」属性，完成了到谓语动词的转换。
这种通过将谓语动词抽丝剥茧拆成「时间＋动作状态」的方式，一方面帮助我们了解时态的本质，也可以使我们毫不费力的记住时态的16种形式。
Section 4 16个时态的进一步理解
上面的梳理建立了时态的基础知识，现在我们就以「动作状态」为基准，来更近一步了解这16个时态的用法。
1，「一般态」
和其他4个「动作状态」不同，「一般态」强调动作的常态性。而「不定态」，「进行态」，「完成态」以及「完成进行态」都不是动作的常态。
比如，关于动作run，
不定态：He wants to run。「想跑还没跑」
进行态：He is running。「正在跑」
完成态：He has run。「跑完了」
这三个都只是「run」这个动作的某一个方面，它们各自都不能构成一个常态。而 常态可以理解为是包含了这三个 「态」的全部动作的一个状态，比如「他天天在跑步」就是一个常态。
根据常态在时间轴上的位置，我们选取不同的「时间」。
一般过去时：He drove to work。「他以前开车上班，表示 现在已经不开车上班了。」
一般现在时：He drives to work。「他开车上班，表示日常行为，是常态。」
一般将来时：He will drive to work。「他将会开车上班，强调未来的常态。」
可以看到，「一般过去时」常常有「 现在不是这样的」意思在，基于这个理由，不变的客观规律，常常都用「一般现在时」来表达，例如：
Plants need sun to grow.
The earth moves around the sun.
「一般过去将来时」表示说话的人站在过去的某个时刻推测将来，如下图。
He said he would come to see me。
谓语动词said表明He是在过去说的，不管come这个动作是在「现在」之前或之后发生，从句都应该用「一般过去将来时」。
2，「进行态」
前面说过，「进行态」强调动作「正在发生」。根据动作发生的时间，我们采用不同的「时间」。
「过去进行时」：He was having a meeting when I called him.
「现在进行时」：He is having a meeting now.
「将来进行时」：He will be having a meeting when I make the call.
「过去将来进行时」：He said that he could not come because he would be having a meeting.
可以看出「进行态」的4中「时态」差别不大，需要注意的是，由于「进行态」的动作的时间范围往往都比较短，所以一般会清楚的指出时间（上句中划横线的部分）。
3，「完成态」
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「现在完成时」
「现在完成时」是最最容易和「一般过去时」混淆的时态，首先是因为它们都可以描述过去的某个时间点。
I did the laundry (yesterday).
I've done the laundry.
两句话的最大差异就是，「 一般过去时」没有说清楚事情是不是完成了，但是 「现在完成时」很清楚的说明事情做完了。
所以，当我们说过去发生的某一件事情的时候，我们要根据说话的重点是「事情发生的时间」还是「事情确定完成」来确定用什么时态，如果重点在于时间，那么我们要用「一般过去时」，当我不关心时间，关心事情的结果或者事情对现在的影响的时候，就用「现在完成时」，让焦点回到事件本身。再看一个例子：
「一般过去时」:I lost my wallet.
只是强调我掉了钱包，没什么别的意思。
「现在完成时」：I've lost my wallet.
我丢了钱包，我没钱了，你能给点钱吗？／我丢了钱包，所以我现在要去取钱，不能和你吃饭了。／我丢了钱包，所以我妈骂了我一顿……
更近一步，「现在完成时」描述的动作往往并不持续，结束了就结束了。而有时候我们需要强调动作的持续性（可参见section 1中关于【 英语私房课】的例子），比如「我在微软工作10年了」。如果你想强调自己还要持续的做下去，那么这个时候就可以不用「现在完成时」，转而用「现在完成进行时」：
I have been working at Microsoft for 10 years.
再举个细节的例子：
「现在完成时」：I have been single for five years.
解释：单身5年，我想恋爱了。／我受不了单身了。／你看我好惨，单身狗当了5年了，没事约约我啊！
「现在完成进行时」：I have been being single for five years.
解释：我很享受单身，而且这个状态还会继续持续。／单身狗当了5年，我觉得还会继续下去吧。
请体会一下两者的不同。
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「过去完成时」
「过去完成时」用来描述在「过去的过去」发生的动作，那么你只要记住「过去完成时」总有一个对应的「一般过去时」，只要是在这个「一般过去时」之前完成的动作，该动作就要用「过去完成时」。
He had studied English before he came to the US.
解释：学习发生在came之前，came本身时过去的动作，所以study用「过去完成时」。
It had already snowed before Monday.
Monday是过去的时间，snow在Monday之前，因此用「过去完成时」。
同理，
如果我们要强调「过去的过去」动作的连续性，即动作从「过去的过去」开始一直连续到过去的这一个时间，我们可以采用「过去完成进行时」。
I had been watching TV before you called me.
解释：强调「看电视」延续性到了called me之前。
He had been driving all day before he went to sleep.
解释：同样强调延续性。
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「将来完成时」和「过去将来完成时」
「将来完成时」从「时间＋动作状态」的角度理解，就表示在将来某一时间之前就能完成的动作。
By the end of this month he will have trained 600 horses.
解释：到这个月底，他就训练了600匹马了。
和「现在完成时」的情况类似，如果近一步讲，我们要强调动作的连续性，即在将来某一时刻之后还将持续下去，我们更倾向于用「将来完成进行时」，即
By the end of this month he will have been training horses for twenty years.
解释：和上一句的区别在于，这句话并没有强调在将来的时间点上，他训练了匹马的数目，也就是没有强调动作对将来时间点的影响。相反，这句话的更多的表示他还将持续training这个动作，因此用「将来完成进行时」更好。
「过去将来完成时」表示从过去看未来已经完成的事情。
He knew by the time he arrived she would have gone home.
「过去将来完成时」常常应用在虚拟语气中。当应用在虚拟语气中的时候，常常 陈述和事实相反的状态，例如
If I had left sooner, I would have been on time.
解释：真实情况是我迟到了。
那么这句话为什么不说成：
If I left sooner, I would be on time.
这是因为英语在陈述一个和事实相反的假设的时候，为了注重逻辑，不能说的似乎和真的一样，因此「 为了和真实的时态做区隔，就将假设语态往过去推了一格」。
错误：If I left sooner, I would be on time. <-- 对 过去的假设
为了和真实的时态区隔，把假设语态往过去推一格，就变成了
正确：If I have left sooner, I would have been on time.
错误：If I am you, I will be rich. <-- 对 现在的假设
同样，为了区隔，将时态往前推一格，变成
正确：If I were you, I would be rich.
4，「完成进行态」
「过去完成进行时」见上面对「过去完成时」的解释，二者可合并理解。
「现在完成进行时」见上面对「现在完成时」的解释，二者可合并理解。
「将来完成进行时」见上面对「将来完成时」的解释，二者可合并理解。
「过去将来完成进行时」和「过去将来完成时」想通，二者可以合并理解。
16种时态中，「过去将来完成进行时」是非常不常用的一个时态，但是并不难理解。和「过去将来完成时」相比，「过去将来完成进行时」依然强调持续的特性。
「过去将来完成时」：I knew by September he would have worked here for 30 years.
解释：强调结果。
「过去将来完成进行时」：I knew by September he would have been working here for 30 years.
解释：强调持续性。
自此总结了英语16个时态的本质和用法。