For example if I wanted to say “He told me what I needed to know.” would I say


Or would it be something different?

And do I always need to use it if I’m telling someone what happened to me?

She told me. 言われた。

He saw me yesterday. 昨日見られた。

Are those the most natural?

Edit: I’m looking for examples in informal speech, thanks!

1 Answer 1


No, there is no rule that you always have to use the passive form.

However, I realized that a Japanese sentence often omits the subject, often implying the subject is the speaker without other context, and that this style makes the sentence in the passive form.

Your example,

He told me what I needed to know.

can be translated to


This Japanese sentence is correct. In fact, if this was an exam of translation, I would answer in this way because there would be no way to mark it as a mistake or blame for missing information. On the other hand, it is not colloquial (or naturally composed Japanese) because it is explicitly stating the subjects (action taker) "彼は" and "私が".

This translation can be modified to


by omitting "私が". There is almost no worry about misunderstanding about 'who needed to know it'. Japanese speakers assume the subject is "私が" by default.

The same sentence can be translated to




These Japanese sentences correspond more to

I was told by him what I needed to know.

and omit the subject "I" at both of the two occurrences. [Version (b) emphasizes 'by him' more than version (b').] The forms (b) and (b') sound more natural than (a). [I am not sure if (b) and (b') are more natural than (a').]

Even more colloquial form will be


This corresponds more to

I heard necessary things from him.

The words are changed, and the sentence might be a little strange as English. However, as a Japanese sentence, version (c) is concise but clear enough that it is delivering the same information as (a), and it is suitable for conversation.

  • thank you! why is it おかなくてはならない instead of just 知っていなくてはならない?i don’t understand the added お and か. and i thought colloquially it’s usually shortened to なきゃ or なくちゃ or ないと?so could this sentence be made with those? Commented Aug 8, 2019 at 2:39
  • '知っていなくてはならない' is also good. '知っておかなくてはならない' can be split to '知っておく'+'なくてはならない' while '知っていなくてはならない' can be split to '知っている'+'なくてはならない'. The difference between the phrases '知っておく' and '知っている' is subtle, and I didn't think about it when I wrote the answer. The former sounds like you are expecting that knowledge might be useful in the future and preparing for such a case, while the latter sounds like stating just the fact. You can generally say 'Aしておく' to mean (hint, or indicate) 'do A (as a preparation for something implied by the context)'.
    – norio
    Commented Aug 8, 2019 at 3:04
  • About なきゃ, なくちゃ, and ないと, you are correct that 'なくてはならない' can be shortened to 'なきゃならない', 'なくちゃならない', 'ないとならない'. (Probably it will be better to replace also 'ならない' with 'いけない'.) The first two forms sound more casual than the third one and sound like spoken in Tokyo and eastern Japan. If you really focus on conversational expressions, you also need to consider where you will be speaking it and with what kind of people. I hope you try learning the Kansai dialect (spoken around Osaka) and others. It will be fun.
    – norio
    Commented Aug 8, 2019 at 3:23
  • got it. i saw 〜ておく recently and didn’t even think about it in association with 知る! and i definitely would like to be exposed to the kansai dialect. would it be more “useful” (more common) than what’s spoken in tokyo? or just something interesting? Commented Aug 8, 2019 at 3:26
  • 1
    Glad to hear that. It will be useful to know the Kansai dialect if you plan to live there or want to watch comedy. Local people usually converse in the local dialect among themselves, and comedians from Osaka tend to keep their original dialect and accents even on nation-wide TV shows. For example, '..しなきゃいけない' becomes '..せなあかん' in Osaka, and I guess you would need some prior knowledge to understand it. Or, maybe you can pick up the patterns quickly once you learn one form of Japanese.
    – norio
    Commented Aug 8, 2019 at 3:47

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