Learning objectives
- Form non-past and past plain forms
- Use sentence-final and noun-modifying forms
- Distinguish judgment, purpose, and change patterns
1. Core plain forms
Verbs use dictionary, nai, ta, and nakatta forms. I-adjectives use the base form, kunai, katta, and kunakatta. Na-adjectives and nouns use da, dewa nai, datta, and dewa nakatta at sentence end; before nouns, na-adjectives use na and nouns normally use no.
2. A connector for larger sentences
Plain forms can modify a following noun and connect to to for quotation, toki for time, n desu for background, shi for multiple reasons, and deshou, kamo shirenai, or hazu da for different levels of judgment.
3. Purpose and change
Use tame ni for an intentional goal and you ni for ability, states, or avoiding an outcome. You ni naru describes a gradual change in ability or state; you ni suru describes a deliberate continuing effort.
Practical examples
1. 田中さんは明日来ると言いました。
Tanaka said that he would come tomorrow.
2. 時間があるとき、日本語を勉強します。
I study Japanese when I have time.
3. どうして遅れたんですか。
Why were you late?
4. 雨が降るかもしれません。
It may rain.
5. 忘れないように、予定を書きました。
I wrote down the schedule so I would not forget.
Common pitfalls
Do not put da before n desu
With nouns and na-adjectives, use nan desu.
Do not confuse hearsay sou with appearance sou
Plain form + sou da reports information; a stem + sou da describes how something looks.
Practice and answers
1. Change shizuka desu to the past plain form.
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shizuka datta / 静かだった2. Complete: 田中さんは来ない（ ）言いました。
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と3. Which fits “practice every day so I can swim”: tame ni or you ni?