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Definition
The grammar pattern 'V-dictionary/V-nai + ことにする' is used to express a personal decision made by the speaker regarding their own future actions. It indicates that the speaker has made a conscious choice to take a certain action. The dictionary form is used for positive decisions, while the 'nai' form is used for negative decisions. This pattern is often used in situations where the speaker is expressing their intention or plan for the future.
Structure
| Form | Pattern | Example |
|---|---|---|
| Dictionary form | V-dictionary + ことにする | 本日から勉強することにする (I will start studying from today) |
| Nai form | V-nai + ことにする | 本日から勉強しないことにする (I will not start studying from today) |
| Te form | V-te + ことにする | 本日から勉強してくれることにする (I will have someone help me study from today) |
Examples
健康のために、今日からお酒を飲まないことにする。
Kenkō no tame ni, kyō kara o-sake o nomanai koto ni suru.
I will stop drinking alcohol from today for my health.
健康のために (for my health), 今日から (from today), お酒を飲まないことにする (stop drinking alcohol)
夏休みは北海道に旅行することにする。
Natsu yasumi wa Hokkaidō ni ryokō suru koto ni suru.
I will go on a trip to Hokkaido during summer vacation.
夏休み (summer vacation), 北海道に (to Hokkaido), 旅行することにする (go on a trip)
迷いましたが、結局このマンションを借りることにする。
Mayoi mashita ga, mōryō kore no manshon o kariru koto ni suru.
Although I was hesitant, I will rent this apartment in the end.
迷いました (I was hesitant), 結局 (in the end), このマンションを借りることにする (rent this apartment)
Context
This pattern is used to express a personal decision or intention, and is often used in situations where the speaker is making a conscious choice. It can be used in both formal and informal situations. Be careful not to confuse this pattern with 'koto ni naru', which is used to express an external decision.
Watch out
This mistake occurs when the speaker is trying to express an external decision, but uses the wrong pattern.
This mistake occurs when the speaker is trying to express an action that is not within their control, but uses this pattern instead.
This mistake occurs when the speaker is trying to express a decision made in the past, but uses the wrong pattern.
Strategy
In the JLPT N3 exam, this pattern may be tested in the reading comprehension section. Be sure to pay attention to the context and use the correct pattern to express the speaker's decision.
In context
Worked examples drawn from JLPT N3 test-style questions. Each sentence shows V-dictionary/V-nai + ことにする used correctly, with a brief note on what the pattern is doing.
健康のために、今日からお酒を飲まないことにしました。
Pattern used: 飲まないことにしました
'koto ni shimashita' indicates a personal decision the speaker has just made.
夏休みは北海道に行くことにしました。
Pattern used: 行くことにしました
Use 'koto ni suru' when you are the one who decided the plan.
迷いましたが、結局このマンションを買うことにしました。
Pattern used: 買うことにしました
'koto ni suru' emphasizes the individual's choice after consideration.
Interactive
健康のために、今日からお酒を______。
Adaptive practice
Our adaptive engine will quiz you on this grammar pattern and track your progress toward mastery.