Natural Japanese — だ, の/んだ & Politeness Traps
Adjective usage, explanatory の, transitivity, comparisons, and practical grammar patterns.
Adjective + だ
- i-Adjectives can take って but not だ:
- 日本語は楽しい。 OK — 日本語は楽しいだ。 X
- Na-Adjectives can take both.
- 日本語は楽しい。 = Japanese is fun.
- Omitting だ (って) before の:
- (after a na-ADJ/Noun): 好きなの OK
- だ is not feminine — women often omit だ in casual speech.
のだ / んだ (Explanatory の)
のだ / んだ statements explain or add information to the context in which they are used. Therefore, they do not stand alone, but require other information (not necessarily verbal) to convey their full meaning.
Common Functions:
- Explanation of reasoning — giving a reason or explanation
- Logical conclusions or discoveries — realizing or concluding something
- Summarizing or reworking — summarizing or rephrasing
- "Sets the scene" (used with ～ている / ～た)
- Alluding information — hinting at something indirectly
- Emphasizing crucial information — stressing an important point
お腹が痛い。昨日仕事を休んだんだ。
My stomach hurt. I missed work yesterday (explaining).
左右どちらの手でも書けるんだ。両利きなんだ。
He can write with either hand. He is ambidextrous (I just realized).
さっきメールを送ったんだ。
Just a few moments ago I sent you an email (by the way).
急いでいるんだ。早く行こう。
We are in a hurry (let me explain). Let us go.
気をつけて。社長の息子なんだ。
Be careful what you say. He is the CEO's son.
～のですか implies a question that is in some way derived from the current situation or discussion.
| Example | Context |
|---|---|
| 風邪を引いているんですか。 | After hearing someone sniffle |
| キノコは好きじゃないんですか。 | Watching someone pick mushrooms off their pizza |
～のか marks "detail" questions — inquiring about specific information, rather than the truth of the sentence as a whole.
パソコンは秋葉原で買ったのか。
Did you buy the computer in Akihabara?
のだ is not used if the predicate of the sentence includes a question word.
If のだ is used where it is not required, it can imply surprise or disbelief.
Tip
のだ combines with the expressions かもしれない and に違いない in 2 possible forms: [の/ん + exp.] or [exp. + のだ/んだ] (no difference in meaning).
Introducing People with これは
- これ portrays the person as an inanimate object — avoid it.
- Replace これ with こちら for people.
こちらは田中さんです。
This is Mr. Tanaka.
Asking About Desires
- Do not use ～たい → ～たいですか in questions directly.
- It is considered overly direct, especially in formal situations.
- Instead use indirect forms or offer suggestions.
ラーメンを食べたいですか。
Do you want to eat ramen? (overly direct)
何がいいですか。
What would be good? (polite alternative)
が/を～たい
- ～たい verb objects can be marked by が or を.
- However, が is regarded as the "correct" particle.
お寿司が/を食べたい。
I want to eat sushi.
"You should..."
- Appropriate for stating a principle.
- Very strong; can sound preachy.
約束は守るべきだ。
You should keep your promises.
- Uses past tense (～た) + 方がいい for giving advice.
早く寝た方がいい。
You should go to bed early.
- ～たらどうですか is the polite form.
- Light and non-imposing.
聞いてみたらどう？
How about asking?
- X 面白いからこの本を読んだほうがいい。
- O 面白いからこの本を読んだらどうですか。
- "You should read this book because it is interesting."
- べき and ほうがいい are too strong for casual suggestions.
Strength
べき (strong) → た方がいい (moderate) → たらどう (casual)
いる vs. ある
- Intransitive + ている = "became — and remains so" (resultant state)
- 窓が開いている。 The window is open.
- Transitive + ている = "—ing" (progression)
- 誰かが窓を開けている。 Someone is opening a window.
- Transitive + てある = "has been —ed and remains so" (intentional result)
ために vs. ように
- V (dictionary form) + ために.
- The subject controls the goal directly.
旅行に行くためにお金を貯めている。
Saving money in order to go on a vacation.
- V (potential / negative / intransitive) + ように.
- Goal is a desired state, not a direct action.
忘れないように書いておく。
Write it down so that I do not forget.
～ないで vs. ～なくて
- Doing something while leaving another action undone.
窓を閉めないで寝た。
I went to sleep without closing the window.
- Expresses a reason or cause for a result.
- The non-occurrence leads to something.
先生に叱られなくてほっとした。
I was relieved that I was not scolded by the teacher.
どれ vs. どちら (どっち)
- A と B のどちらがおいしい？ = 2 options
- A と B と C のどれがおいしい？ = 3+ options
A と B のどちらがおいしい？
Which is tastier, A or B? (2 options)
A と B と C のどれがおいしい？
Which is tastiest among A, B, and C? (3+ options)
～よう vs. ～そう
- Based on the overall situation or reasoning.
高そうだ。
It seems expensive (the situation makes it seem so).
- Based on physical appearance or visual impression.
高そう。
It looks expensive (the appearance makes it seem so).
はい、そうです
- NOUN って → はい、そうです。
- Use そうです to affirm noun predicates.
- Use direct affirmation for adjective predicates: はい、高いです。
はい、高いです。
Yes, it is expensive. (adjective — direct)
はい、そうです。
Yes, that is correct. (noun — そうです)
～のだから
- Cannot be used with reasons which are not self-evident to the listener.
- Used to push with a reason that is shared knowledge.
X お腹が痛かったんだから学校を休んだ。
My stomach hurt so I missed school. (wrong — のだから)
O お腹が痛かったから学校を休んだ。
My stomach hurt so I missed school. (correct — から)
Using ね
| Speaker has experience | Speaker has no experience | |
|---|---|---|
| Listener has experience | Direct + ね | Indirect (+ね) |
| Listener has no experience | Direct | Indirect |
～らしい is used when the speaker has no direct experience (hearsay).
Pronunciation
Pronunciation difference is more stress-based than sound length.
Transitivity
Intransitive (自動詞) vs. Transitive (他動詞)
自動詞 (vi): describe a self-occurring action & don't have an object. 他動詞 (vt): describe an action caused by a person and can take a direct object (を).
車が止まる
A car stops (by itself — intransitive)
車を止める
Someone stops a car (transitive)
X 車を止まる = bad Japanese
| Intransitive (vi) | Transitive (vt) |
|---|---|
| 変わる | 変える |
| 冷える | 冷やす |
| 冷める | 冷ます |
| 起きる | 起こす |
| 始まる | 始める |
| 下りる | 下ろす |
| 下がる | 下げる |
| 落ちる | 落とす |
| 逃げる | 逃がす |
| 動く | 動かす |
| 壊れる | 壊す |
| 破れる | 破る |
| 消える | 消す |
| 開く | 開ける |
| 当たる | 当てる |
| 起き上がる | ... |
Descriptive Uses of する
- Used with sensory, physical, or cost descriptions.
細い腕をしている
to have thin arms
怖い顔をする
to make a scary face
甘い味がする
there is a sweet taste
3千円をする
to cost 3000 yen
覚える vs. 思い出す
- The act of memorizing or learning something.
出会った日のことを覚えてる？
Do you remember the day we first met? (what it was like)
- The act of recalling something previously known.
彼の名前を思い出した。確かに山崎だった。
I remembered his name. I am sure it was Yamazaki.
Key Difference
覚える = storing information into memory. 思い出す = retrieving information from memory. ※ 出会った日を覚えてる？ = "Do you remember what day we first met?" (asking the calendar date)
Icons & Badges Reference
Usage Icons
Form Badges
Verb Form Suffixes
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