Verb て-form + おく

[Do in Advance / Leave As Is]

Connection: Verb て-form + おく

This pattern has two distinct meanings:

1. Preparation/Doing in advance: Do something now in preparation for later use or for future convenience.

• 明日のために買っておく (buy in advance for tomorrow)
• 会議の前に資料を読んでおく (read the materials before the meeting)

2. Leave as is: Leave something in a certain state, either intentionally maintaining it or allowing it to remain.

• そのままにしておく (leave it as is)
• ドアを開けておく (leave the door open)

Casual contraction: In casual speech, ておく often contracts to とく:

• 買っておく → 買っとく
• 読んでおく → 読んどく

Common usage: Often paired with もう (already) to emphasize completion of preparation: もう予約しておいた (I already made a reservation).

Examples:

• 試験のために単語を覚えておいてください。(Please memorize the vocabulary in advance for the exam.)
• 荷物はここに置いておきます。(I'll leave the luggage here.)
• 念のため、傘を持っておこう。(Just in case, I'll bring an umbrella.)