The word こと literally means "thing" or "matter," but in Japanese grammar it mainly serves as a nominalizer — turning verbs into nouns. Built on top of this, it forms four must-know N3 patterns.
1. ことができる — Ability
Verb dictionary form + ことができる = can do something:
| Example | Meaning |
|---|---|
| 私は中国語を話すことができる。 | I can speak Chinese. |
| この図書館では本を借りることができます。 | You can borrow books at this library. |
ことができる is more formal and written than the potential form (話せる). In casual speech, the potential form is more common.
2. たことがある — Experience
Verb た-form + ことがある = have done something (at least once):
The negative form uses ことがない, meaning "have never done."
たことがある emphasizes a life experience — something you've done at least once. It's not for recent events like "I ate ramen yesterday."
3. ことがある — Sometimes Happens
Verb dictionary form + ことがある = something sometimes happens (occasional habit):
Compared to たことがある
| Pattern | Meaning | Time sense |
|---|---|---|
| 富士山に登ったことがある | I've climbed Mt. Fuji | Life experience |
| 朝ご飯を食べないことがある | I sometimes skip breakfast | Recurring habit |
Key difference: た-form = experience (at least once), dictionary form = habit (happens occasionally).
4. とは〜ことです — Defining Things
A とは B ことです = "A" means "B":
| Example | Meaning |
|---|---|
| 門限とは、門を閉める時刻のことです。 | "Curfew" means the time when the gate closes. |
| 通勤とは、家から職場まで行くことです。 | "Commuting" means going from home to the workplace. |
とは introduces the concept being defined, and ことです wraps up the definition. This pattern is very useful for explaining words and concepts.
Bonus: こと as a Basic Nominalizer
At its most fundamental, こと turns verbs into nouns so they can serve as subjects or objects:
When the subject is an abstract concept like a dream, job, or hobby, use こと for nominalization (not の).
Quick Reference
| Pattern | Conjugation | Meaning | Example |
|---|---|---|---|
| ことができる | Dict. form + ことができる | Can do | 泳ぐことができる |
| たことがある | た-form + ことがある | Have done | 行ったことがある |
| ことがある | Dict. form + ことがある | Sometimes | 忘れることがある |
| とは〜ことです | A とは B ことです | A means B | 節約とは… |
Self-Test
Q1. How do you say "I've been skiing before" using たことがある?
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スキーをしたことがある。 Verb た-form (した) + ことがある = a past experience.
Q2. What does 「電車が遅れることがある」 mean? Is it experience or habit?
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It means "The train is sometimes late." This is the habit/occasional usage — dictionary form (遅れる) + ことがある means "this situation happens from time to time." If it were 遅れたことがある, it would mean "has been late before" (experience).
Q3. In 「門限とは、門を閉める時刻のことです」, what roles do とは and ことです play?
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- とは = introduces the concept being defined ("as for curfew...")
- ことです = provides the definition ("...it means the time the gate closes")
- Together they form a standard definition pattern.