Differences between plain form and polite past tense
The differences between the plain form and polite past tense in Japanese mainly lie in their usage and conjugation:
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The plain past form is used in casual, informal conversations typically among friends, family, or people of the same status. The polite past form is used in formal or respectful situations, such as speaking with strangers, superiors, or in professional settings. 6
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Conjugation of verbs differs between the two forms. The plain past is often formed by replacing the verb ending in the dictionary form, e.g., 食べる (taberu, to eat) becomes 食べた (tabeta). The polite past tense adds ました (mashita) to the stem of the verb, e.g., 食べます → 食べました (tabemashita). 5, 7, 6
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The plain past form does not require a question particle for questions, often using just a question mark in writing. In contrast, the polite past form uses the question particle か (ka) at the sentence end for questions. 6
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Both forms express the past tense, referring to actions completed in the past. The plain past form also functions within casual speech, while polite past tense emphasizes respect and formality. 4, 6
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Politeness level is the main distinction; the plain form represents informal speech, and the polite form sets a formal, respectful tone. 9
Summary Table of Differences
| Aspect | Plain Past Tense | Polite Past Tense |
|---|---|---|
| Usage | Casual, informal situations | Formal, respectful situations |
| Verb Conjugation | 食べる → 食べた (tabeta) | 食べます → 食べました (tabemashita) |
| Question Form | Question mark only (e.g., 食べた？) | Uses question particle か (e.g., 食べましたか) |
| Tone | Informal | Polite, respectful |
| Audience | Friends, family, equals | Superiors, strangers, formal contexts |
This concise guide describes the key differences between plain form and polite past tense in Japanese verb usage and social context. 7, 5, 9, 6