A2 Pinyin & Tones 14 min read Medium

Chinese Tone Rules: The 'No' and 'One' Chameleons (不/一)

Change 不 and 一 to 2nd tone before 4th tones to keep your Chinese smooth and natural.
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Grammar Rule in 30 Seconds

The words {不|bù} and {一|yī} change their tones based on the sound that follows them.

  • {不|bù} becomes 2nd tone before a 4th tone: {不对|búduì}.
  • {一|yī} becomes 4th tone before 1st, 2nd, and 3rd tones: {一天|yìtiān}.
  • {一|yī} becomes 2nd tone before a 4th tone: {一个|yígè}.
不/一 + [Next Tone] = [New Tone]

Overview

Chinese phonetics are characterized by tones, which distinguish word meanings. However, these tones are not static. Mandarin Chinese features Tone Sandhi (变调 biàndiào), a phenomenon where the original tone of a syllable changes based on the tone of the following syllable.

This adjustment is crucial for achieving natural, fluid speech and is an intrinsic part of Mandarin's prosody. It serves two primary linguistic functions: articulatory ease and acoustic distinctiveness. Without these changes, certain tone sequences would be phonetically awkward or taxing to produce, and the rhythmic flow of the language would be severely disrupted.

This article focuses on the two most common and critical tone chameleons: 不 (bù, no/not) and 一 (yī, one).

The original dictionary tones for 不 (4th tone) and 一 (1st tone) frequently undergo obligatory modifications when followed by other syllables. These changes are not optional stylistic variations; they are fundamental pronunciation rules that distinguish a native-like speaker from one who sounds stiff or unnatural. Mastering these tone sandhi rules for 不 and 一 is a significant step towards both phonetic accuracy and greater comprehension in real-world Chinese communication.

Understanding the underlying principles of why these changes occur—primarily to avoid sequences of identical or phonetically challenging tones—will aid in their acquisition.

How This Grammar Works

Tone Sandhi rules operate by modifying the actual spoken tone of a character while its written Pinyin tone mark often remains unchanged (particularly for 不 and 一). The change is always determined by the original tone of the character immediately following the chameleon character. This means you must consider the tone context of a two-syllable sequence, or sometimes longer phrases, to correctly apply the rules.
The most common trigger for tone changes in 不 and 一 is the fourth tone ('). A sequence of two consecutive fourth tones, such as bù + shì (bù shì), would involve two sharp, falling intonations in quick succession. This is phonetically demanding and can sound abrupt.
Tone Sandhi resolves this by changing the first tone in the sequence, allowing for a smoother transition. Similarly, 一 changes its tone not only before a fourth tone but also before first, second, or third tones, demonstrating its more complex chameleon behavior. These shifts are about creating a balanced phonetic contour, preventing a monotonous or choppy delivery, and ensuring that each syllable maintains sufficient acoustic prominence.
The changes are deeply ingrained in the Chinese phonological system, reflecting a preference for alternating tone patterns rather than repetitive ones.
For learners, it is vital to distinguish between the base tone (the tone listed in dictionaries) and the surface tone (the tone actually pronounced in context). While written Pinyin usually displays the base tone for pedagogical clarity, your vocal production must adhere to the surface tone rules for natural communication. This principle highlights that Pinyin transcription is a representation of underlying phonology, not always a direct map to surface pronunciation.

Formation Pattern

1
Let's systematically break down the tone sandhi rules for 不 and 一. These rules are obligatory in spoken Mandarin. Adhering to these patterns will significantly improve your phonetic accuracy.
2
1. The 不 (bù) Rule:
3
The character 不 (meaning "no" or "not") has an original 4th tone. Its tone changes under one specific condition.
4
| Original Tone of 不 | Tone of Following Character | Resulting Tone of 不 |
5
|:---------------------:|:---------------------------:|:-----------------------:|
6
| bù (4th tone) | 4th tone | bú (2nd tone) |
7
| bù (4th tone) | 1st, 2nd, 3rd, Neutral tone | bù (4th tone) |
8
Rule 1: 不 before a 4th tone becomes 2nd tone (bú).
9
This is the most critical change for 不. When 不 is followed by another 4th tone character, its tone shifts from a falling 4th tone to a rising 2nd tone. This prevents the awkward sequence of two consecutive falling tones.
10
Example: 不 + 是 (shì, 4th tone) → 不是 (bú shì, "is not")
11
Example: 不 + 去 (qù, 4th tone) → 不去 (bú qù, "not go")
12
Example: 不 + 对 (duì, 4th tone) → 不对 (bú duì, "incorrect")
13
Rule 2: 不 before 1st, 2nd, 3rd, or neutral tone remains 4th tone (bù).
14
In all other tone contexts, 不 retains its original 4th tone.
15
Example: 不 + 听 (tīng, 1st tone) → 不听 (bù tīng, "not listen")
16
Example: 不 + 来 (lái, 2nd tone) → 不来 (bù lái, "not come")
17
Example: 不 + 想 (xiǎng, 3rd tone) → 不想 (bù xiǎng, "not want")
18
Example: 不 + 客气 (kèqi, neutral tone) → 不客气 (bù kèqi, "you're welcome")
19
Special Case: 不 in V 不 V (Verb-不-Verb) constructions.
20
When 不 is used in a reduplicated verb question structure, it typically loses its tone and becomes a neutral tone (bu). This applies to common patterns like verb + 不 + verb (e.g., 是不是, 去不去).
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Example: 是 不 是 (shì bu shì, "is it or not?")
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Example: 看 不 看 (kàn bu kàn, "to watch or not?")
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2. The 一 (yī) Rule:
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The character 一 (meaning "one" or "a/an") has an original 1st tone. Its tone changes under two main conditions, and also has special behavior in numerical sequences.
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| Original Tone of 一 | Tone of Following Character | Resulting Tone of 一 |
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|:---------------------:|:-----------------------------:|:-----------------------:|
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| yī (1st tone) | 4th tone | yí (2nd tone) |
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| yī (1st tone) | 1st, 2nd, or 3rd tone | yì (4th tone) |
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| yī (1st tone) | (Isolated, counting, ordinal) | yī (1st tone) |
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Rule 1: 一 before a 4th tone becomes 2nd tone (yí).
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Similar to 不, 一 shifts to a rising 2nd tone when followed by a 4th tone character, breaking up the potentially monotonous or awkward sequence.
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Example: 一 + 个 (gè, 4th tone) → 一个 (yí gè, "one (of something)")
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Example: 一 + 次 (cì, 4th tone) → 一次 (yí cì, "one time")
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Example: 一 + 样 (yàng, 4th tone) → 一样 (yí yàng, "the same")
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Rule 2: 一 before 1st, 2nd, or 3rd tone becomes 4th tone (yì).
36
This is a unique characteristic of 一. Before any other non-4th tone character, 一 transforms into a falling 4th tone. This ensures a clear contrast and prevents a sequence of identical tones (e.g., two 1st tones) or other potentially less distinct combinations.
37
Example: 一 + 杯 (bēi, 1st tone) → 一杯 (yì bēi, "one cup")
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Example: 一 + 年 (nián, 2nd tone) → 一年 (yì nián, "one year")
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Example: 一 + 点 (diǎn, 3rd tone) → 一点 (yì diǎn, "a little")
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Special Case 1: 一 in numerical sequences or standing alone.
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When 一 is used as a standalone number, for counting, in phone numbers, addresses, or as part of an ordinal number (第 一), it typically retains its original 1st tone (yī). This preserves its numerical identity. This also applies when 一 is at the end of a phrase or sentence.
42
Example: 一 二 三 (yī èr sān, "one, two, three")
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Example: 第一 (dì yī, "first")
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Example: 手机号码是 五 一 八... (shǒujī hàomǎ shì wǔ yī bā..., "The phone number is 518...")
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Special Case 2: 一 in V 一 V (Verb-一-Verb) constructions.
46
Similar to 不, when 一 is placed between a reduplicated verb, it often becomes a neutral tone (yi). This structure creates a light, often casual, sense of "to do for a bit" or "to try."
47
Example: 听 一 听 (tīng yi tīng, "listen for a bit/listen and see")
48
Example: 看 一 看 (kàn yi kàn, "take a look")

When To Use It

These tone sandhi rules for 不 and 一 are not optional embellishments; they are integral to correct Mandarin pronunciation. Applying them demonstrates phonological fluency and significantly enhances intelligibility and naturalness for native speakers. You use these rules constantly in everyday speech, making them high-frequency phonetic phenomena.
  • Negation with 不: Any time you negate a verb, adjective, or adverb using 不, you must apply the tone change if the following character is a 4th tone. For instance, you will always say bú shì (不是, is not), bú qù (不去, not go), bú duì (不对, incorrect), and bú kàn (不看, not watch). Ignoring this makes your speech sound labored and foreign.
  • Quantification with 一: When 一 is used with measure words (量词, liàngcí), which is its most frequent usage, its tone will almost always change. For example, 一个 (yí gè, one 个), 一本 (yì běn, one 本 - for books), 一杯 (yì bēi, one cup), 一张 (yì zhāng, one 张 - for flat objects). The exceptions are when 一 is used for pure counting or in ordinal numbers, as detailed above.
  • Auxiliary Verb Phrases: In expressions like 看一看 (kàn yi kàn, take a look) or 试一试 (shì yi shì, have a try), the neutral tone forms of 一 are indispensable. Similarly, in rhetorical questions like 好不好 (hǎo bu hǎo, good or not good?), 不 must be neutral. These structures are extremely common in daily dialogue.
  • Fixed Expressions and Idioms: Many common four-character idioms (成语 chéngyǔ) and fixed phrases incorporate these sandhi rules. For instance, 一帆风顺 (yì fān fēng shùn, plain sailing) and 不言而喻 (bù yán ér yù, self-evident). Pronouncing these without the correct tone changes will disrupt the established rhythm and sound incorrect to a native ear. The consistency of these changes across a vast vocabulary reinforces their fundamental nature.
Fundamentally, using these tone changes ensures your speech aligns with Mandarin's inherent rhythm and flow. Mandarin prefers a melodic, undulating tone contour. The sandhi rules actively prevent sequences that would create a choppy, staccato effect, thereby promoting smoother articulation and improved perception of your speech by listeners.
It's a key aspect of sounding natural and being easily understood in spontaneous conversation.

Common Mistakes

Learners frequently encounter specific pitfalls when navigating the tone sandhi of 不 and 一. Recognizing these common errors and understanding their underlying causes is crucial for effective correction and mastery.
  • "Dictionary Brain" Syndrome: The most prevalent mistake is clinging to the dictionary's base tone for 不 and 一 in all contexts. For example, consistently pronouncing 不是 as bù shì (two 4th tones) or 一个 as yī gè (a 1st tone followed by a 4th tone). This happens because Pinyin often writes the base tone, leading learners to speak it without modification. The consequence is speech that sounds effortful, aggressive, or unnaturally staccato. Native speakers will understand, but it requires more cognitive effort on their part to process, and your pronunciation will sound distinctly non-native.
  • Over-generalizing 一's changes: Some learners, upon grasping 一's chameleon nature, apply the changes too broadly. They might change 一's tone even when it functions as a pure numeral, such as in phone numbers (一二三, yī èr sān) or ordinal numbers (第一, dì yī). In these contexts, 一 retains its original 1st tone to maintain its clear numerical identity. Changing it (e.g., yí èr sān or dì yí) would confuse the numerical value or sound simply incorrect.
  • Confusing with 3rd Tone Sandhi: While both 不/一 sandhi and 3rd Tone Sandhi involve tone changes, their rules and triggers are distinct. 3rd Tone Sandhi states that when two 3rd tones appear consecutively (e.g., nǐ hǎo), the first 3rd tone changes to a 2nd tone (ní hǎo). The key differences are:
  • Scope: 3rd Tone Sandhi applies universally to any two consecutive 3rd tones. 不/一 sandhi is specific to these two characters.
  • Written Form: In some pedagogical materials, 3rd Tone Sandhi might be explicitly written (e.g., ní hǎo). For 不 and 一, the base tone (bù, yī) is almost always written, regardless of spoken change.
  • Trigger: 3rd Tone Sandhi is triggered by another 3rd tone. 不/一 sandhi is primarily triggered by 4th tones (for 不) or a variety of tones (for 一). Misapplication of one rule for the other is a common source of error.
  • Pausing between words: When you hesitate or pause briefly between 不/一 and the following character, it can disrupt the phonetic unit and cause you to revert to the base tone. These pairs should be treated as a single, fluid phonetic unit, where the sandhi occurs naturally as part of the articulation process. Practicing them as single-word chunks (不是, 一个) rather than individual characters (不... 是) helps solidify the correct pronunciation.
  • Writing the changed tone: Learners sometimes attempt to write bú, yí, or yì in Pinyin when the tone has changed in speech. While this might aid personal learning, standard Pinyin orthography for 不 and 一 typically retains the base tone (bù, yī) to reflect the character's lexical identity. This is a source of confusion because the written form does not always reflect the spoken reality. The exception, as mentioned, is 3rd Tone Sandhi, which sometimes explicitly shows the change.
To overcome these mistakes, focused listening, conscious repetition, and diligent self-correction are essential. Pay attention to how native speakers pronounce these characters in various contexts, and actively imitate their patterns.

Real Conversations

Understanding 不 and 一 tone sandhi is not merely an academic exercise; it is fundamental to participating in genuine, natural Chinese conversations. These rules are applied subconsciously by native speakers and are pervasive in all forms of communication, from casual dialogue to formal presentations, and even in digital communication where pinyin is often typed.

- Daily Interactions & Ordering: You will frequently hear 不 and 一 in their changed forms. When ordering food or groceries, 一个 (yí gè, one item) is ubiquitous. You'll never hear a native speaker say yī gè with the flat first tone. For example:

- "我想要一个苹果。" (Wǒ xiǎng yào yí gè píngguǒ., "I want one apple.")

- "你是不是中国人？" (Nǐ shì bu shì Zhōngguórén?, "Are you Chinese or not?") - Note 不 as neutral tone.

- Refusals and Negations: The 2nd tone for 不 before a 4th tone is particularly prominent in common negations:

- "不用谢。" (Bú yòng xiè., "No need to thank.") - 用 (yòng) is 4th tone.

- "不好意思。" (Bù hǎo yìsi., "Excuse me/Sorry.") - 好 (hǎo) is 3rd tone, so 不 remains 4th tone.

- "我不知道。" (Wǒ bù zhīdào., "I don't know.") - 知 (zhī) is 1st tone, so 不 remains 4th tone.

- Giving Instructions/Making Suggestions: The neutral tone 一 in V 一 V structures conveys a casual, tentative, or encouraging tone:

- "你听一听这个歌。" (Nǐ tīng yi tīng zhège gē., "You listen to this song for a bit.")

- "我们走一走吧。" (Wǒmen zǒu yi zǒu ba., "Let's take a walk.")

- Expressing Uncertainty or Lack of Specificity: 一点 (yì diǎn, a little bit) or 一些 (yì xiē, some) are vital for expressing small quantities:

- "请给我一点水。" (Qǐng gěi wǒ yì diǎn shuǐ., "Please give me a little water.")

- "他有一些问题。" (Tā yǒu yì xiē wèntí., "He has some problems.")

- Digital Communication: Even when typing Pinyin without tone marks, native speakers instinctively read and mentally process the tone changes. For instance, if someone texts bu qu for "not go," a native speaker automatically pronounces it bú qù. This highlights that the sandhi is an internal, cognitive phonetic rule, not just a surface feature of spoken language. Mispronouncing these subtle yet consistent tone shifts can sometimes lead to a listener taking slightly longer to process your speech, or perceiving you as less confident in your Chinese abilities, even if the grammatical structure is correct. It is a key marker of fluency.

Quick FAQ

  • Q: Do I need to write the changed tone in Pinyin?

Generally, no. Standard Pinyin for 不 and 一 typically maintains their original dictionary tones (bù and yī) even when spoken tones change. This is for consistency in lexical representation. You must, however, speak the changed tones. An exception might be personal learning notes, but formal writing and textbooks usually do not change the tone mark for these two characters.

  • Q: Why does 一 sometimes stay 1st tone even before a 4th tone, like in 第一 (dì yī, 'first')?

This occurs because in 第一, 一 functions purely as an ordinal numeral (the number 'one' in a sequence) rather than as a classifier or part of a measure word phrase. When 一 emphasizes its numerical value or appears in a count, it often retains its base 1st tone. Similarly, in phone numbers or when simply counting (一二三), it stays 1st tone.

  • Q: Will native speakers understand me if I don't use these tone changes?

Yes, in most cases, they will understand the literal meaning. However, your speech will sound less natural, more effortful, and possibly choppy or foreign. It requires extra cognitive effort for them to process, as your pronunciation deviates from the expected phonetic patterns. It's a key aspect of sounding fluent and integrated into the language's natural rhythm.

  • Q: Are there other characters that undergo similar tone changes?

While 不 and 一 are the most prominent and consistently applied, some regional variations or specific contexts might see other numerical characters like 七 (qī, seven) and 八 (bā, eight) also undergo tone changes before a 4th tone (e.g., qí cì, bá bēi), primarily in southern Mandarin dialects. However, for standard A2 Mandarin, focusing intently on 不 and 一 is sufficient and crucial.

  • Q: How can I effectively practice and master these tone sandhi rules?

The most effective methods are focused listening and shadowing. Actively listen to native speakers in authentic contexts (podcasts, dramas, conversations) and pay close attention to how they pronounce 不 and 一. Then, practice shadowing them—imitating their speech as closely as possible. Record yourself and compare with native audio. Consistent exposure and deliberate practice will eventually make these changes feel intuitive and automatic, building crucial muscle memory for natural Chinese pronunciation.

Tone Sandhi Rules for 不 and 一

Character Original Tone Followed by New Tone
不
4th
1st/2nd/3rd
4th
不
4th
4th
2nd
一
1st
1st/2nd/3rd
4th
一
1st
4th
2nd
一
1st
Alone/End
1st

Quick Reference

Target Before 4th Tone Before 1st/2nd/3rd
不
2nd tone
4th tone
一
2nd tone
4th tone

Meanings

Tone sandhi is a phonetic phenomenon where the tone of a character changes depending on the tone of the following character to make speech flow more naturally.

1

Negation

The word {不|bù} is used to negate verbs and adjectives.

“{我不吃|wǒ bù chī}”

“{他不累|tā bú lèi}”

2

Cardinal Number

The word {一|yī} represents the number one.

“{一个|yígè}”

“{一本书|yì běn shū}”

Reference Table

Reference table for Chinese Tone Rules: The 'No' and 'One' Chameleons (不/一)
Form Structure Example
Negation
不 + 4th tone
{不对|búduì}
Negation
不 + 1st tone
{不吃|bù chī}
Number
一 + 4th tone
{一个|yígè}
Number
一 + 1st tone
{一天|yìtiān}
Number
一 + 2nd tone
{一年|yì nián}
Number
一 + 3rd tone
{一本|yì běn}
Isolated
一
{第一|dì yī}

Formality Spectrum

Formal
{我不想要|wǒ bù xiǎngyào}

{我不想要|wǒ bù xiǎngyào} (Shopping)

Neutral
{我不想要|wǒ bù xiǎngyào}

{我不想要|wǒ bù xiǎngyào} (Shopping)

Informal
{我不想要|wǒ bù xiǎngyào}

{我不想要|wǒ bù xiǎngyào} (Shopping)

Slang
{不要了|bú yào le}

{不要了|bú yào le} (Shopping)

The Chameleon Tones

Tone Sandhi

不 (Bù)

  • 不 + 4th Becomes 2nd

一 (Yī)

  • 一 + 4th Becomes 2nd
  • 一 + 1/2/3 Becomes 4th
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Examples by Level

1

{我不去|wǒ bú qù}

I am not going.

2

{一个苹果|yígè píngguǒ}

One apple.

3

{不是|bú shì}

It is not.

4

{一天|yìtiān}

One day.

1

{我不买这个|wǒ bù mǎi zhège}

I am not buying this.

2

{一起走|yìqǐ zǒu}

Walk together.

3

{不对|búduì}

That's not right.

4

{一本书|yì běn shū}

One book.

1

{不高兴|bù gāoxìng}

Not happy.

2

{一万块|yí wàn kuài}

Ten thousand yuan.

3

{不累|bù lèi}

Not tired.

4

{一月|yí yuè}

January.

1

{不得不|bù dé bù}

Have to.

2

{一模一样|yì mú yí yàng}

Exactly the same.

3

{不简单|bù jiǎndān}

Not simple.

4

{一而再|yì ér zài}

Again and again.

1

{不折不扣|bù zhé bú kòu}

One hundred percent.

2

{一针见血|yì zhēn jiàn xiě}

Hit the nail on the head.

3

{不约而同|bù yuē ér tóng}

Coincidentally.

4

{一无所有|yì wú suǒ yǒu}

Have nothing.

1

{不置可否|bú zhì kě fǒu}

Non-committal.

2

{一落千丈|yí luò qiān zhàng}

Drop drastically.

3

{不偏不倚|bù piān bù yǐ}

Impartial.

4

{一气呵成|yí qì hē chéng}

Done in one go.

Easily Confused

Chinese Tone Rules: The 'No' and 'One' Chameleons (不/一) vs Third Tone Sandhi

Learners confuse sandhi rules for 3rd tones with 4th tone rules.

Chinese Tone Rules: The 'No' and 'One' Chameleons (不/一) vs Neutral Tone

Learners think the neutral tone is a sandhi rule.

Chinese Tone Rules: The 'No' and 'One' Chameleons (不/一) vs Original Tone

Learners forget when to use the original tone.

Common Mistakes

✗

{不吃|bú chī}

✓

{不吃|bù chī}

不 only changes before 4th tone.
✗

{一个|yī gè}

✓

{一个|yígè}

一 changes before 4th tone.
✗

{不是|bù shì}

✓

{不是|bú shì}

是 is 4th tone, so 不 must change.
✗

{一天|yī tiān}

✓

{一天|yìtiān}

天 is 1st tone, so 一 must change.
✗

{不累|bú lèi}

✓

{不累|bù lèi}

累 is 4th tone, but wait—it's 3rd tone! So 不 stays 4th.
✗

{一起|yī qǐ}

✓

{一起|yìqǐ}

起 is 3rd tone, so 一 changes to 4th.
✗

{不买|bú mǎi}

✓

{不买|bù mǎi}

买 is 3rd tone, so 不 stays 4th.
✗

{一月|yī yuè}

✓

{一月|yí yuè}

月 is 4th tone, so 一 changes to 2nd.
✗

{不高兴|bú gāoxìng}

✓

{不高兴|bù gāoxìng}

高兴 is 1st/1st, so 不 stays 4th.
✗

{一万|yī wàn}

✓

{一万|yí wàn}

万 is 4th tone, so 一 changes to 2nd.
✗

{不折不扣|bù zhé bù kòu}

✓

{不折不扣|bù zhé bú kòu}

扣 is 4th tone, so the second 不 changes.
✗

{一针见血|yī zhēn jiàn xiě}

✓

{一针见血|yì zhēn jiàn xiě}

针 is 1st tone, so 一 changes to 4th.
✗

{不置可否|bù zhì kě fǒu}

✓

{不置可否|bú zhì kě fǒu}

置 is 4th tone, so 不 changes.
✗

{一落千丈|yī luò qiān zhàng}

✓

{一落千丈|yí luò qiān zhàng}

落 is 4th tone, so 一 changes to 2nd.

Sentence Patterns

我不___。

我有一个___。

这___不对。

这事儿___简单。

Real World Usage

Ordering food constant

{一个汉堡|yígè hànbǎo}

Texting very common

{不对|búduì}

Job interview common

{不简单|bù jiǎndān}

Travel common

{一张票|yì zhāng piào}

Social media common

{不客气|bú kèqì}

Food delivery app constant

{一个|yígè}

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💡

Listen to Natives

Listen to podcasts and try to catch the 'bú' and 'yí' sounds.
⚠️

Don't Over-Apply

Only change 'bù' before 4th tone. Don't change it before 1st, 2nd, or 3rd.
🎯

Shadowing

Repeat native audio until the sandhi feels natural.
💬

Regional Differences

Be aware that some dialects might have different sandhi rules.

Smart Tips

Change it to 2nd tone.

{不 对|bù duì} → {不对|búduì}

Change it to 2nd tone.

{一 个|yī gè} → {一个|yígè}

Change it to 4th tone.

{一 天|yī tiān} → {一天|yìtiān}

Keep it 4th tone.

{不 吃|bú chī} → {不吃|bù chī}

Pronunciation

bù (4th) -> bú (2nd)

Tone Sandhi

The pitch contour shifts to accommodate the next syllable's pitch.

High-Falling

bù (4th) -> bú (2nd)

Signals a change in tone due to the following character.

Memorize It

Mnemonic

Remember: 'No' changes only before 4th, but 'One' changes before everything else.

Visual Association

Imagine a chameleon named 'Bù' that only changes color when it sees a big 4th-tone monster. Imagine a chameleon named 'Yī' that is so shy it changes color whenever it sees anyone else.

Rhyme

Bù before four turns to two, Yī before four turns to two, Yī before others turns to four, now you know the tone lore!

Story

Bù was a 4th tone king. He only bowed (to 2nd tone) when he met the 4th tone Queen. Yī was a 1st tone prince. He was so polite he bowed (to 4th tone) to everyone he met, except when he was alone.

Word Web

{不对|búduì}{一个|yígè}{一天|yìtiān}{不吃|bù chī}{一起|yìqǐ}{一年|yì nián}

Challenge

Spend 5 minutes reading a Chinese menu out loud, focusing specifically on every '不' and '一' you see.

Cultural Notes

Standard Mandarin strictly follows these rules in media and education.

Similar rules apply, though some speakers may be more relaxed in casual speech.

They often find tone sandhi difficult because Cantonese has more tones and different sandhi rules.

These rules evolved to facilitate the rhythmic flow of spoken Mandarin.

Conversation Starters

“

你想要一个吗？

“

这不对吗？

“

你一天吃几顿饭？

“

你觉得这简单吗？

Journal Prompts

Describe your day using 'one' (一) for time.
Write about something you don't (不) like.
Explain why something is not (不) correct.
Reflect on a difficult (不简单) task you finished.

Common Mistakes

Incorrect

Correct

Incorrect

Correct

Incorrect

Correct

Incorrect

Correct

Sign up free to see all tips

Test Yourself

Fill in the correct tone for 不.

我___去 (bù/bú)

✓ Correct! ✗ Not quite. Correct answer: bù
去 is 4th tone, so it stays bù.
Choose the correct pronunciation. Multiple Choice

一个 (yī gè / yígè)

✓ Correct! ✗ Not quite. Correct answer: yígè
个 is 4th tone.
Correct the tone. Error Correction

Find and fix the mistake:

不吃 (bú chī)

✓ Correct! ✗ Not quite. Correct answer: bù chī
吃 is 1st tone.
Change the tone based on the following word. Sentence Transformation

一 + 天

✓ Correct! ✗ Not quite. Correct answer: yìtiān
天 is 1st tone.
Is this rule correct? True False Rule

不 always changes to 2nd tone.

✓ Correct! ✗ Not quite. Correct answer: False
Only before 4th tone.
Complete the dialogue. Dialogue Completion

A: 你要买吗？ B: 不___ (bù/bú)

✓ Correct! ✗ Not quite. Correct answer: bù
买 is 3rd tone.
Build a sentence. Sentence Building

一 / 本 / 书

✓ Correct! ✗ Not quite. Correct answer: yì běn shū
本 is 3rd tone.
Sort by tone. Grammar Sorting

Which one uses 2nd tone?

✓ Correct! ✗ Not quite. Correct answer: {不对|búduì}
不对 uses 4th tone.

Score: /8

Practice Exercises

8 exercises
Fill in the correct tone for 不.

我___去 (bù/bú)

✓ Correct! ✗ Not quite. Correct answer: bù
去 is 4th tone, so it stays bù.
Choose the correct pronunciation. Multiple Choice

一个 (yī gè / yígè)

✓ Correct! ✗ Not quite. Correct answer: yígè
个 is 4th tone.
Correct the tone. Error Correction

Find and fix the mistake:

不吃 (bú chī)

✓ Correct! ✗ Not quite. Correct answer: bù chī
吃 is 1st tone.
Change the tone based on the following word. Sentence Transformation

一 + 天

✓ Correct! ✗ Not quite. Correct answer: yìtiān
天 is 1st tone.
Is this rule correct? True False Rule

不 always changes to 2nd tone.

✓ Correct! ✗ Not quite. Correct answer: False
Only before 4th tone.
Complete the dialogue. Dialogue Completion

A: 你要买吗？ B: 不___ (bù/bú)

✓ Correct! ✗ Not quite. Correct answer: bù
买 is 3rd tone.
Build a sentence. Sentence Building

一 / 本 / 书

✓ Correct! ✗ Not quite. Correct answer: yì běn shū
本 is 3rd tone.
Sort by tone. Grammar Sorting

Which one uses 2nd tone?

✓ Correct! ✗ Not quite. Correct answer: {不对|búduì}
不对 uses 4th tone.

Score: /8

Practice Bank

10 exercises
How do you say 'incorrect' naturally? Multiple Choice

Which is the natural pronunciation of {不对|bùduì}?

✓ Correct! ✗ Not quite. Correct answer: bú duì
Ordering one person (一个人). Fill in the Blank

{一|___}{个|gè}{人|rén}。

✓ Correct! ✗ Not quite. Correct answer: yí
Translate 'Not bad!' (usually used for movies or food). Translation

Not bad!

✓ Correct! ✗ Not quite. Correct answer: {不错|búcuò}
Fix the tone of '一' in 'one piece'. Error Correction

{一|yī}{件|jiàn}{衣服|yīfu}

✓ Correct! ✗ Not quite. Correct answer: {一|yí}{件|jiàn}{衣服|yīfu}
Match the phrase to its spoken pinyin tone. Match Pairs

Match the following:

✓ Correct! ✗ Not quite. Correct answer: All matches correct.
Put the words in order for 'I am not tired'. Sentence Reorder

tired / I / not

✓ Correct! ✗ Not quite. Correct answer: {我|wǒ} {不|bú} {累|lèi}
How is '一' pronounced in 'First' (第一)? Multiple Choice

{第一|dìyī}

✓ Correct! ✗ Not quite. Correct answer: dì yī
One thousand (一千). Fill in the Blank

{一|___}{千|qiān}。

✓ Correct! ✗ Not quite. Correct answer: yì
Check the tone of '不' in 'Not going'. Error Correction

{不|bù}{去|qù}

✓ Correct! ✗ Not quite. Correct answer: {不|bú}{去|qù}
Translate 'Same' (Same/Alike). Translation

The same

✓ Correct! ✗ Not quite. Correct answer: {一样|yíyàng}

Score: /10

FAQ (8)

To make speech flow better.

No, only when it's a number or modifier.

You will still be understood, but you'll sound less natural.

Yes, for standard Mandarin.

Very few, mostly in specific dialects.

Listen and repeat.

No, only in speech.

Mostly, yes.

Scaffolded Practice

1

1

2

2

3

3

4

4

Mastery Progress

Needs Practice

Improving

Strong

Mastered

Sign up free to practice

In Other Languages

Spanish none

None

Spanish uses stress, not pitch, to distinguish words.

French partial

Liaison

Liaison involves consonants, sandhi involves pitch.

German none

None

German is a stress-timed language.

Japanese moderate

Pitch Accent

Japanese pitch is about word-level accent, not character-level sandhi.

Arabic none

None

Arabic uses root-and-pattern morphology.

Chinese high

Tone Sandhi

It is the standard for the language.

Learning Path

Prerequisites

Previous
Tone Changes - 3rd Tone Combination
Next
Chinese Dates & Calendar: Year, Month, Day

Learn These First

A1 Requires

Four Tones + Neutral Tone

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A1

Chinese Syllables: Pinyin & Tones Structure

Overview Every language constructs its words from smaller sound units. In English, these units often manifest as complex...
A1

Four Tones + Neutral Tone

Overview Mandarin Chinese is a **tonal language**. This is the single most important concept for a beginning learner to...
A2

Tone Changes - 3rd Tone Combination

Overview The **3rd tone combination rule** (or **third tone sandhi**) is a fundamental aspect of spoken Mandarin Chinese...
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