Comparing "bu" and "mei"

Both 不 (bù) and 没 (méi) can be placed in front of a verb or adjective to negate its meaning. However, 不 and 没 are not usually interchangeable, so it's important to learn when you must use 不 as opposed to 没, and vice versa.

不 is for negating in the present and future

不 is generally used to negate an action that you do not want to do or do not intend to do (in the future). So expressing things like "I don't want to go" or "I'm not going" would be uses of 不.

Structure

Subject + 不 + Verb

Examples

Whether it's "don't wanna do it" or "not gonna do it," use 不:

• 我 今天 晚上 不 吃 饭。Tonight I won't eat.
• 我 今天 晚上 不 想 吃 饭。Tonight I don't want to eat.
• 他 不 去 公园。He won't go to the park.
• 他 不 要 去 公园。He doesn't want to go to the park.

不 is used to negate habitual actions

不 can be used to negate habitual actions, to express what you just aren't in the habit of doing, such as eating meat, or watching TV, or drinking alcohol. This is simply done by placing 不 in front of the verb.

Structure

Subject + 不 + Verb + Object

Examples

• 我 不 吃 肉。I don't eat meat.
• 我 不 看 电视。I don't watch TV.
• 我 不 喝 酒。I don't drink alcohol.

Please note that, while it is grammatically correct to use 没 in all the sentences above, 没 does not negate any habitual actions. The sentences above, if they contained 没 instead of 不, would express that the speaker didn't do the named activity (at one particular point in the past). So it would not be about habitual actions.

不 is normally used with adjectives

When it comes to a simple negation of an adjective (e.g. "not Adj"), use 不.

Structure

不 + Adj

Examples

• 我 不 高兴。I am not happy.
• 她 不 漂亮。She is not pretty.
• 你的 女朋友 不 难看。Your girlfriend is not ugly.
• 我们 不 饿。We're not hungry.
• 你 不 聪明。You are not smart.

不 is used to ask questions

There a couple ways to use 不 to ask questions. One such way is through affirmative-negative questions. This is done by stating a verb and then immediately repeating that verb in a negative state (with 不):

Structure

Subject + Verb + 不 + Verb + Object

Examples

• 你 是 不 是 我 的 老师。Are you my teacher? (Literally: You are-not are my teacher?)
• 今天 你 来 不 来？Are you coming today? (Literally: Today you come-not come?)
• 你 喜 不 喜欢 吃 中国菜。Do you like to Chinese food? (Literally: Do you like-not like Chinese food>)

不 can also be used to form tag questions. Tag questions use the positive-negative question form, but are placed at the end of the sentence. Tag questions are used to seek approval or acceptance for a statement, very similar to the English "OK?" or "right?" You can't use 没 for this.

• 我们 去 吃饭，好 不 好 ？ Let's go eat, is that OK?
• 你 是 我的 同学，对 不 对 ？ You are my classmate, right?
• 我们 喝 水，好 没 好。Let's drink water, OK does not have OK?
• 你 得 上 课，对 没 对。You should go to class, right not have right?

没 is used to negate past actions

没 and 没有 can both be used to negate actions that occurred in the past, or to say that something has not happened yet.

Structure

Subject + 没(有) + Verb + Object

Examples

• 他 没有 打 电话 给 我。He did not give me a call.
• 他 没有 上课。He did not go to class.
• 我 昨天 没 喝 葡萄酒。I did not drink wine yesterday.
• 我 昨天 不 喝 葡萄酒 。I not drink wine yesterday.

There are a few things worth noting in these examples. For one, it is still grammatically correct to leave out the 有 in the sentences using 没有. Also, the sentence using 不 would be grammatically correct, if not for the 昨天 ("yesterday") telling us that it is definitely the past we're talking about. That incorrect sentence using 不 would translate into *"I don't drink wine yesterday" as opposed to "I didn't drink wine yesterday."

Only 没 is used to negate 有

没 can be used to negate the verb 有 ("to have") to mean "do not have." You can only use 没 to convey this meaning. It is grammatically incorrect to use 不 to negate 有.

Structure

Subject + 没有 + Object

Examples

• 我 没有 钱。I don't have money.
• 我 不 有 钱。I not have money.
• 他 没有 女朋友。He doesn't have a girlfriend.
• 他 不 有 女朋友。He not have girlfriend.

There are times when you can leave out 有 entirely while still expressing 没有 (meaning "to not have" or "there is no"). One well-known example of this is 没办法 ("there is no way" [that's gonna happen]). Both 没 and 没有 are correct, however.

• 我 没 办法。I don't have a way.
• 我 没有 办法。I don't have a way.

(You can also use 没办法 to express other meanings.)

没 is used to make comparisons

没 or 没有 can be used to make simple comparisons meaning "not as... as":

Structure

Noun 1 + 没有 + Noun 2 + Adjective

Examples

• 我 的 钱 没有 他 的 钱 多。(Literally: "My money does not have his money many.")My money isn't as much as his.
• 你 的 钱 不 有 他 的 钱 多。 My money not have much as his.
• 你 没有 我 高兴。You are not as happy as me. (Literally: you do not have my happiness.)
• 你 不 有 我 高兴。You not have my happy.

You can only use 没 or 没有 for this purpose, and not 不.

不 is used almost exclusively with some verbs

Certain verbs just don't get negated by 没 or 没有 ever. These include the verbs 是 ("to be") and 在 ("to be (in a place)"), as well as some psychological verbs such as 知道 ("to know") and 认识 ("to know (a person)"). For these verbs, it's best to just take them on a case-by-case basis. Being aware of their existence can save you a fair bit of confusion.

• 他 以前 不 是 我的 朋友 。 He was not my friend before.
• 他 以前 没 是 我的 朋友 。 He did not have my friend before.
• 昨天 我 不 在 家 。 I was not home yesterday.
• 昨天 我 没 在 家 。 I did not have home yesterday.
• 昨天 我 不 知道 。 I didn't know yesterday.
• 昨天 我 没 知道 。 I did not have know yesterday.
• 他 以前 不 认识 她 。 He did not know her before.
• 他 以前 没 认识 她 。 He not have know her before.

Note that in non-standard Mandarin you might encounter exceptions to this rule. It's still useful to know the rule!

Sources and further reading

Websites

• http://www.docin.com/p-20925643.html
• http://wenku.baidu.com/view/e2e8eb2ce2bd960590c67703.html

Books

• Chinese: An Essential Grammar, Second Edition (pp. 141-4) →buy
• Integrated Chinese: Level 1, Part 1 (3rd ed) (pp. 86) →buy
• New Practical Chinese Reader 1 (新实用汉语课本1) (pp. 87) →buy
• New Practical Chinese Reader 1 (新实用汉语课本1)(2nd ed) (pp. 102, 250-1) →buy
• Chinese: An Essential Grammar, Second Edition (pp. 54-5) →buy
• New Practical Chinese Reader 3 (新实用汉语课本3) (pp. 33-4) →buy
• Chinese: An Essential Grammar, Second Edition (pp. 51) →buy
• 现代汉语八百词（增订本） (pp. 382) →buy
• Practicing HSK Grammar (语法精讲精炼) (pp. 32) →buy
• 现代汉语八百词（增订本） (pp. 383) →buy
• Integrated Chinese: Level 1, Part 1 (3rd ed) (pp. 31) →buy
• Integrated Chinese: Level 1, Part 2 (1st ed) (pp. 85-86)　→buy
• New Practical Chinese Reader 1 (新实用汉语课本1)(2nd ed) (pp. 218) →buy
• Reference:Chinese Grammar - Broken down into 100 items - Basic and Intermediate Levels (汉语语法百项讲练 - 初中级))(不 没p.156)→buy