Collins Chinese Dictionary Plus (3rd edition), 2011:
不
bù 副
1 (用于否定句) not
- 我不喜欢(歡)游泳。 Wǒ bù xǐhuān yóuyǒng. I don't like swimming.
- 不法 bùfǎ illegal
- 不轨(軌) bùguǐ
undisciplined - 不诚(誠)实(實) bù chéngshí
dishonest
- 不人道 bù réndào
inhumane - 他不抽烟(煙)。 Tā bù chōuyān.
He doesn't smoke.
2 (用于否定回答) no
- "你累了吧?""不, 不累。" "Nǐ lèi le ba? ""Bù, bùlèi. " "Are you tired?""No, I'm not."
- "你不忙吧?""不,很忙。" "Nǐ bù máng ba?""Bù,hěn máng."
"You're not busy, are you?""Yes, I am."
3 (表示不能)
- 我吃不下。 Wǒ chī bù xià. I can't eat it.
- 你找不到她吗(嗎)? Nǐ zhǎo bù dào tā ma?
Can't you find her?
- 他中文学(學)不好。 Tā zhōngwén xué bù hǎo.
He's not good at Chinese.
4 (方) (用于问句)
- 你饿(餓)不? Nǐ è bù? Are you hungry?
5 (跟`就是'搭配)
- 周(週)末,她不是购(購)物,就是看电(電)视(視)。 Zhōumò, tā bùshì gòuwù,jiùshì kàn diànshì. If she doesn't go shopping at the weekend she'll watch TV.
3
(客套: 不用)
- 不客气(氣)。 Bù kèqi. Please don't mention it.
- 不谢(謝)。 Bù xiè. You're welcome.
Negating sentences in Chinese is very straightforward: just use 不(bù) before the verb. E.g. 我不喝酒。(Wǒ bù hējiǔ) (I don't drink alcohol). The only exception is the verb 有(yǒu) , to have, for which you must use 没(méi) . E.g. 我没有钱。(Wǒ méiyǒu qián.) (I don't have any money). 不(bù) is fourth tone unless it is followed by another fourth tone syllable, in which case it is usually pronounced as a second tone, eg. 不要(búyào) . For more information on tones, please see the introduction.