1、Different focuses of negation
"不 (bù)" negates subjective will, attitude, habit, or nature, meaning "actively not wanting / not agreeing".
"没 (有) (méi (yǒu))" negates objectively occurring facts, the completion of an action, or the existence of something, meaning "objectively not happening / not existing".
2、Types of Verbs/Adjectives They Collocate With
"不 (bù)" can collocate with stative verbs (such as 喜欢 (xǐhuān, like), 相信 (xiāngxìn, believe), 愿意 (yuànyì, be willing)) and adjectives (such as 漂亮 (piàoliang, beautiful), 快 (kuài, fast)), expressing a long-term state or subjective judgment.
"没 (有) (méi (yǒu))" mostly collocates with action verbs (such as 吃 (chī, eat), 去 (qù, go), 看 (kàn, watch)), indicating that an action has not occurred or has not been completed; it can also be followed by a noun to express negation of existence (e.g., "没水 (méi shuǐ, there is no water)").
3、Different time associations
"不 (bù)" can be used in the present, future, and can also express habitual negation (without a clear time limit).
"没 (有) (méi (yǒu))" is mainly used for past or current objective results (emphasizing "not occurring within a period of time that has already happened").
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