う-Verb (Negative-Past)う - Verbs (Negative-past tense)

Both forms express the negative past ('did not'), but the formation differs depending on whether the verb is a る-Verb or う-Verb. For example, 食べなかった (for 食べる, a る-Verb) means 'I did not eat,' while 買わなかった (for 買う, a う-Verb) means 'I did not buy.' Both are plain forms used in casual speech or other grammatical patterns.

These forms express the negative ('does not' or 'will not') of う-Verbs, with a difference in tense. The う-Verb (Negative) expresses a lack of future or habitual action (e.g., 買わない = 'I don't buy' or 'I won't buy'). The う-Verb (Negative-Past) expresses a lack of past action (e.g., 買わなかった = 'I didn't buy'). Both are plain forms used in casual speech or other grammatical patterns.

These two forms are used with う-Verbs to express the idea of having done or not having done a particular action in the past. The difference is whether the meaning is affirmative ('did') or negative ('did not'). For example, 買った means 'I bought,' while 買わなかった means 'I did not buy.' Both are plain forms used in casual speech or as part of other grammatical forms.