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!


1 Answer 1


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。

  • 1
    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
    Jun 13, 2017 at 16:33
  • But you can "forget" something you learn ;-)
    – mootmoot
    Jun 13, 2017 at 16:35
  • 1
    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
    Jun 13, 2017 at 16:41
  • How would "我之前知道" be understood? Is it incorrect?
    – Somniare
    Jun 14, 2017 at 11:01
  • @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
    Jun 14, 2017 at 11:20

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