Preparation (~te oku)
〜ておく
~ておく expresses doing something in advance as preparation or leaving something in a certain state.
Pattern
Te-form + おく | Casual: Te-form → ~とく / ~どく
Explanation
~ておく is used to express doing something beforehand in preparation for a future situation, or leaving something as it is intentionally. It carries a sense of foresight and planning.
In casual speech, ~ておく contracts to ~とく, and ~でおく contracts to ~どく. These shortened forms are very common. For example, 買っておく becomes 買っとく, and 読んでおく becomes 読んどく.
The second usage — leaving something in its current state — is also important. For example, 窓を開けておく means 'leave the window open' (on purpose). This differs from simply opening the window; it implies the intentional decision to maintain that state.
Examples
旅行の前にホテルを予約しておいた。
りょこうのまえにほてるをよやくしておいた。
ryokou no mae ni hoteru wo yoyaku shite oita.
I booked the hotel before the trip. (preparation)
明日のために弁当を作っておく。
あしたのためにべんとうをつくっておく。
ashita no tame ni bentou wo tsukutte oku.
I'll make a lunch box in advance for tomorrow.
エアコンをつけとくね。
えあこんをつけとくね。
eakon wo tsuketoku ne.
I'll leave the air conditioner on, okay? (casual)
この資料を読んどいてください。
このしりょうをよんどいてください。
kono shiryou wo yondoite kudasai.
Please read this material beforehand.
Common Mistakes
Wrong
食べるおく
Correct
食べておく
おく must follow the te-form of the verb, not the dictionary form.
Wrong
買っておく → 買っどく
Correct
買っとく
When the te-form uses て, the contraction is とく. どく is only for で-ending te-forms.
Wrong
ドアを閉めておいた (when you simply closed it)
Correct
ドアを閉めた
Only use ておく when there is a sense of preparation or intentionally leaving a state. For simple past actions, use plain past tense.
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