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Kau Conjugation

買う (kau) means "to buy" in Japanese. Non-past, plain (dictionary form): 私 / あなた / 彼 / 彼女 / 私たち / あなたたち / 彼ら (watashi / anata / kare / kanojo / watashitachi / anatatachi / karera) 買う (kau). Below: all 30 tenses we teach, with examples.

Non-past, plain (dictionary form) 辞書形・非過去形

Base form; states habitual actions, general truths, and future events. Also the citation/dictionary form of the verb.

Non-past, polite 丁寧形（〜ます）

ます attaches to the ます-stem (連用形) for the polite non-past; used in nearly all speech to non-intimates.

Past, plain た形

Formed by attaching た to the same stem used for the te-form (with the same 音便 sound changes for godan verbs); marks a completed action or past state, and is also used for "have done X" experience with こと.

Past, polite 丁寧形（〜ました）

ました replaces ます for a completed polite action.

Negative, non-past, plain ない形

The ない-form: drop the final u-row kana of a godan verb and add あない (with う→わ), or drop る from an ichidan verb and add ない; states that something is not/will not be done.

Negative, non-past, polite 丁寧形（〜ません）

ません replaces ます for the polite negative.

Negative, past, plain なかった形

Replace the final い of the ない-form with かった; "did not do".

Negative, past, polite 丁寧形（〜ませんでした）

ませんでした is the polite past negative, used in all polite registers (there is no shortened polite equivalent).

Te-form て形

The connective form: links clauses ("do X and then Y"), makes polite requests with ください, and is the base for the progressive, permission (てもいい) and prohibition (てはいけない). Godan verbs undergo 音便 sound changes (く→いて, ぐ→いで, う/つ/る→って, ぬ/ぶ/む→んで, す→して).

Progressive (plain / polite) 〜ている・〜ています

て形 + いる/います expresses an action in progress ("is doing"), a resulting state ("is open"), or with habitual verbs a repeated action; casual speech contracts it to 〜てる.

Volitional, plain 意向形（〜う・〜よう）

Godan verbs shift the final kana to the お-row and add う; ichidan verbs drop る and add よう; する→しよう, 来る→来よう. Used alone ("let's...") or before と思う ("I plan to...").

Volitional, polite 丁寧形（〜ましょう）

ましょう replaces ます; the standard polite "let's...", and ましょうか offers to do something for someone.

Potential, non-past 可能形（非過去）

"Can do / is able to do"; conjugates exactly like an ichidan verb from this point on (potential-た, potential-て, etc.).

Potential, negative 可能形（否定）

"Cannot do"; formed by conjugating the potential form as an ichidan negative.

Passive, non-past 受身形（非過去）

"Is done (to); gets done (to)"; conjugates like an ichidan verb from here on.

Passive, negative 受身形（否定）

"Is not done (to)"; the ichidan negative of the passive stem.

Causative 使役形

"Make/let (someone) do"; conjugates like an ichidan verb.

Causative-passive 使役受身形

"Be made to do (unwillingly)"; godan verbs commonly contract 〜せられる to 〜される in speech.

Conditional ば 仮定形（〜ば）

Godan verbs shift to the え-row and add ば; ichidan verbs drop る and add れば; general/logical condition, "if... (then generally)".

Conditional たら 〜たら形

Past-tense form + ら; the most versatile conditional, covering "if" and "when" for a specific one-time situation, and usable before commands, invitations and questions (unlike と).

Conditional なら 〜なら形

Dictionary form (or noun/adjective) + なら; comments on or reacts to a premise, often reordering the natural sequence ("if you're going, I'll come too"), and can also mean "if it's about...".

Conditional と 〜と形

Dictionary form + と; an automatic, mechanical or habitual "whenever X happens, Y always follows" (natural laws, directions, habits); cannot be followed by a command, invitation or request.

Imperative (blunt, affirmative) 命令形

Godan: shift to the え-row; ichidan: drop る and add ろ (or literary よ); する→しろ／せよ (せよ is literary); 来る→来い. Direct and often harsh; used in emergencies, sports, signs and fiction.

Softened command 〜なさい 〜なさい

ます-stem + なさい; a firm but not harsh command, typically parent-to-child or teacher-to-student.

Prohibitive (blunt) 〜な 禁止形（〜な）

Dictionary form + な; a blunt "don't do", common among men and in casual/rough speech, signs, and fiction.

Polite request 〜てください 〜てください

て形 + ください; the standard, polite way to ask someone to do something.

Honorific 尊敬語

Regular pattern: お + ます-stem + になる. Common verbs use irregular suppletive forms instead (shown here for these verbs where they exist).

Humble 謙譲語

Regular pattern: お + ます-stem + する／いたす. Common verbs use irregular suppletive forms instead (shown here for these verbs where they exist).

Masu-stem (continuative) 連用形

The bare stem before ます, たい, なさい, or another verb in a compound; also used to join two clauses in written/formal style instead of the て形 (立ち上がり、話し始めた).

Dictionary form (citation form) 辞書形

The plain non-past form, used as the headword in dictionaries and before こと/の/前に to turn the verb into a noun-like phrase.

Examples

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