<p>Do take note that some sentence meaning otherwise under special context.</p>

<p>"知道了"  is a good example. </p>

<p>Even 知道 carry out the meaning of "know", but "知道了"  in some conversions mean "okay"(noded). </p>

<p>For example： </p>

<pre><code>Q：“如果经过超市，顺带买瓶酱油”  If you happens to pass the store, buy me a bottle of soyasauce.

A：“知道了！” Okay （or you can reply "好的!"）
</code></pre>

<p>In different dialect such as Cantonese, sometimes it uses as "understood" rather than 清楚了， 了解了, 明白了</p>

<pre><code>我知道了, 你是说如果把醋倒进去它就会溶掉。 Now I understood, you mean if you pour in vinegar, it will melt.  
</code></pre>

<p>Because 过 in Mandarin carry the meaning "over/pass"(instead of before) in certain conditions, so you can't use it. As mentioned by @Alex, you can't "un-learn", "de-notify" something.  </p>

<p>In case of "know", to say "I already know that", you can't say, "知道过” ， but "我【已经】知道了”， “我【早】知道了”。 </p>

<p>However, you can say "I learn it before but I forget".</p>

<p>这把戏， 我从前【学过】， 不过我忘了。 </p>

CC BY-SA 3.0
2017-06-13T16:33:43.030Z
You can add in your answer that one cannot use 过 in conjunction with 知道 - technically once you know something, you cannot ' unknown' it
Alex
CC BY-SA 3.0
2017-06-13T16:35:18.387Z
But you can "forget" something you learn ;-)
mootmoot
CC BY-SA 3.0
2017-06-13T16:41:41.693Z
hah that's true you can forget it but it's different from unknowing it.  The info is in your brain, you just failed to retrieves it.  Unless brainwash is a thing in the future
Alex
CC BY-SA 3.0
2017-06-14T11:01:03.923Z
How would "我之前知道" be understood? Is it incorrect?
Somniare
CC BY-SA 3.0
2017-06-14T11:20:28.297Z
@Somniare  "之前知道" use to describe associated events.  Please post a new question and ask the different of "之前" versus  ”过“.
mootmoot
CC BY-SA 3.0
2017-06-14T11:42:15.563Z
@mootmoot [said question](https://chinese.stackexchange.com/questions/24122/what-would-the-meaning-of-%e4%b9%8b%e5%89%8d%e7%9f%a5%e9%81%93-be-and-%e4%b9%8b%e5%89%8d%e7%9f%a5%e9%81%93%e4%ba%86)
Somniare
CC BY-SA 3.0
2017-06-13T16:07:57.237Z
2017-06-13T16:59:54.250Z
2017-06-13T16:59:54.250Z
mootmoot
<p>I am investigating the use of 知道 in the past tense. As "知道了“ does not clearly mean "knew" but could be more closely translated as "now I know!", a change of state from not knowing to knowing.
How would one translate "I knew"? (As in, I did know before, but now no longer do)</p>

<p>Thanks in Advance!</p>

CC BY-SA 3.0
2017-06-13T14:36:11.560Z
see previous Q:  https://chinese.stackexchange.com/questions/20856/which-verbs-do-not-go-with-%e4%ba%86-and-or-%e8%bf%87  esp. ＂知道＂不能用动态助词 （了、着，过）
suggestion：enter "I once knew" into jukuu, get 9 relevant samples (1-9), esp. 6.我曾经认识
user6065
CC BY-SA 3.0
2017-06-13T15:43:38.537Z
@user6065 : it is a flawed answer.
mootmoot
CC BY-SA 3.0
2017-06-13T20:17:47.480Z
Q  quoted in comment #1 says: 但表示＂由不知道到知道‌​＂、＂由无到有＂这一改变时，可以用＂了＂,
知道了 can be used for "changing from not knowing to knowing", 我曾经认识 "I once knew" irrelevant, how about
  "no longer know" 不再知道／现在不知道
user6065
CC BY-SA 3.0
2017-06-14T04:17:29.403Z
Some people used it on the Web. However, those sentences are probably not the case you are talking about because they do not mean "unknown" again.

[你听过*知道过*哪些咎由自取的故事。？](https://www.zhihu.com/question/60375126) ... 

[我们*知道过了*这位艺术家。](http://www.duolingo.cn/comment/6960835) ... 

[我从未*知道过*有什么苦恼是不能为一小时的读书所排遣的。](http://zaojv.com/s2724887.html) ... 

[那*知道过*的，必得一次又一次地重新知道；懂得过的，还要再来一次，才能真的接近懂。](http://www.jianshu.com/p/78598cdb5099) ... 

[一個曾經愛過，而且*知道過*關係的人，他​​是可以單獨的](http://blog.xuite.net/tonycjones/twblog/171988447)
SLS
<grammar><word-choice><word-requests>
Can one use 过 in conjunction with 知道?
# Can one use 过 in conjunction with 知道?

(Asked by: username_0 on 2017-06-13)

I am investigating the use of 知道 in the past tense. As "知道了“ does not clearly mean "knew" but could be more closely translated as "now I know!", a change of state from not knowing to knowing.
How would one translate "I knew"? (As in, I did know before, but now no longer do)

Thanks in Advance!

**Tags:** grammar, word-choice, word-requests
> **Comments:**
> **username_1**: see previous Q:  https://chinese.stackexchange.com/questions/20856/which-verbs-do-not-go-with-%e4%ba%86-and-or-%e8%bf%87  esp. ＂知道＂不能用动态助词 （了、着，过） suggestion：enter "I once knew" into jukuu, get 9 relevant samples (1-9), esp. 6.我曾经认识  
> **username_2**: @user6065 : it is a flawed answer.  
> **username_1**: Q  quoted in comment #1 says: 但表示＂由不知道到知道‌​＂、＂由无到有＂这一改变时，可以用＂了＂, 知道了 can be used for "changing from not knowing to knowing", 我曾经认识 "I once knew" irrelevant, how about   "no longer know" 不再知道／现在不知道  
> **username_3**: Some people used it on the Web. However, those sentences are probably not the case you are talking about because they do not mean "unknown" again.  [你听过*知道过*哪些咎由自取的故事。？](https://www.zhihu.com/question/60375126) ...   [我们*知道过了*这位艺术家。](http://www.duolingo.cn/comment/6960835) ...   [我从未*知道过*有什么苦恼是不能为一小时的读书所排遣的。](http://zaojv.com/s2724887.html) ...   [那*知道过*的，必得一次又一次地重新知道；懂得过的，还要再来一次，才能真的接近懂。](http://www.jianshu.com/p/78598cdb5099) ...   [一個曾經愛過，而且*知道過*關係的人，他​​是可以單獨的](http://blog.xuite.net/tonycjones/twblog/171988447)  

---

## 1 answers

### Answer by username_2 on 2017-06-13. Score: 2 | Accepted answer

Do take note that some sentence meaning otherwise under special context.
"知道了"  is a good example. 
Even 知道 carry out the meaning of "know", but "知道了"  in some conversions mean "okay"(noded). 
For example： 
Q：“如果经过超市，顺带买瓶酱油”  If you happens to pass the store, buy me a bottle of soyasauce.

A：“知道了！” Okay （or you can reply "好的!"）

In different dialect such as Cantonese, sometimes it uses as "understood" rather than 清楚了， 了解了, 明白了
我知道了, 你是说如果把醋倒进去它就会溶掉。 Now I understood, you mean if you pour in vinegar, it will melt.  

Because 过 in Mandarin carry the meaning "over/pass"(instead of before) in certain conditions, so you can't use it. As mentioned by @Alex, you can't "un-learn", "de-notify" something.  
In case of "know", to say "I already know that", you can't say, "知道过” ， but "我【已经】知道了”， “我【早】知道了”。 
However, you can say "I learn it before but I forget".
这把戏， 我从前【学过】， 不过我忘了。

> **Comments:**
> **username_4**: You can add in your answer that one cannot use 过 in conjunction with 知道 - technically once you know something, you cannot ' unknown' it  
> **username_2**: But you can "forget" something you learn ;-)  
> **username_4**: hah that's true you can forget it but it's different from unknowing it.  The info is in your brain, you just failed to retrieves it.  Unless brainwash is a thing in the future  
> **username_0**: How would "我之前知道" be understood? Is it incorrect?  
> **username_2**: @Somniare  "之前知道" use to describe associated events.  Please post a new question and ask the different of "之前" versus  ”过“.  
> **username_0**: @mootmoot [said question](https://chinese.stackexchange.com/questions/24122/what-would-the-meaning-of-%e4%b9%8b%e5%89%8d%e7%9f%a5%e9%81%93-be-and-%e4%b9%8b%e5%89%8d%e7%9f%a5%e9%81%93%e4%ba%86)  

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