In Genki II textbook (second edition page 114 and 115) you are tasked with creating sentences using ~時. The problem is their answers seem to contradict what is written in "A dictionary of basic Japanese grammar" (page 493).

Ex IV.A.2 shows a picture of a student not understanding something, we are supposed to create a sentence meaning "When I don't understand something I ask someone". So the order seems to be I don't understand something , and then I ask someone, which according to dictionary asks for past + 時 + present (わからなかった時人にききます), while the answer is present + 時 + present (わからない時人にききます).

Similarly, ex. IV.A.4 shows a person being homesick. We are supposed to construct a sentence meaning "When I get homesick, I call my parents", which again seems to call for past + 時 + present, and instead it's translated as ホームシックの時両親に電話をかけます.

I'm pretty sure I'm misunderstanding something.

  • 2
    But you are asking while you still do not understand. The state of not understanding isn't finished when you ask.
    – Blavius
    Feb 1, 2016 at 22:23
  • @Blavius ohhhhhh... I'm a fool. That's the answer, thank you.
    – Tribski
    Feb 1, 2016 at 22:27
  • Related: Explaining Tense in Japanese Feb 1, 2016 at 23:27

1 Answer 1


The past-tense ~た時 pattern is used when the action is completed relative to the main clause.

The present-tense ~る時 pattern is used when the action has not yet been completed relative to the main clause.

A common example to illustrate the difference:

On the way to Japan, I bought a camera. (The action of "going" isn't complete yet.)
When I went to Japan (after arriving), I bought a camera.

This is reflected in your sentences as well:

When I don't understand something I ask someone.

Your lack of understanding is not yet completed when you ask. It would not make sense to ask once you understand. Therefore, the present tense is necessary before 時.

Likewise, you call your parents while being homesick, not after being homesick. So the present tense is used in that sentence also.

  • Okay, but then in the next exercise I'm again asked to create ~時 sentenses. In the example, from 道に迷う・親切そうな人に道を聞く they made 道に迷った時親切そうな人に道を聞きます. In this situation, the action of being lost is not yet complete, and yet it's in the past
    – Tribski
    Feb 1, 2016 at 22:54
  • Yes, thanks for bringing that up. I should have said it must be completed relative to the main clause. You will be lost by the time you ask.
    – Blavius
    Feb 1, 2016 at 23:19
  • The state of being lost isn't completed when you ask for help; just like the state of lack of understanding isn't completed when you ask someone. So why is the tense different: 道に迷ったとき vs わからないとき?
    – max
    Jan 16, 2022 at 1:01

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