How to Say “Must” with 得 (děi)
得 (děi) is the auxiliary “must / have to”: Subject + 得 + Verb Phrase. 我们得走了 (“we have to go now”), 你得道歉 (“you must apologize”). It's the everyday spoken word for real obligation, lighter than the formal 必须. The catch is the character: 得 is read děi (“must,” before the verb) but also de (the complement particle, after the verb), so 你走得很快 is a totally different 得.
Why this trips learners up
得 (děi) is the auxiliary verb “must / have to.” The frame is Subject + 得 + Verb Phrase, and it marks a real, practical obligation: 我们得走了 (“we have to go now”), 是你的错，你得道歉 (“it's your fault, you must apologize”), 在学校就得听老师的话 (“at school you've got to listen to the teacher”). It's the natural spoken word for “have to / gotta,” a bit more everyday than the formal 必须 (bìxū), and it often ends with 了 when a situation has changed: 时间不早了，我得回家了 (“it's getting late, I have to head home”).
Now the thing that trips everyone up: the character 得 has more than one reading. As the modal “must” it's read děi and sits before the verb (你得走, “you must go”). But the very same character is also the structural particle de, which sits after a verb to link a complement or degree (你走得很快, “you walk fast”). Same shape on the page, two different sounds and two different jobs, decided entirely by position: before the verb it's the “must” děi, after the verb it's the particle de.
Chinese happily puts both in one sentence, which is great practice: 你病得太厉害了，得去看医生 (“you're really sick, you must see a doctor”), where the first 得 is the particle de (病得太厉害, “sick to a serious degree”) and the second is the modal děi (得去, “must go”). Likewise 你得穿得正式一点 (“you must dress a bit more formally”): 得穿 is děi, 穿得 is de.
Two more things to lock in. First, the negative of 得 (děi, “must”) is 不用 / 不必 (“don't need to”), never 不得: “you must go” 你得去 becomes 你不用去 (“you don't have to go”), because 不得 (bùdé) means “must not,” the opposite. Second, 得 already means “must,” so don't add 要 after it (not 得要, just 得). And keep it apart from 应该: 你应该道歉 is “you should apologize” (advice), while 你得道歉 is “you have to” (no real choice). Quick test: if it comes before the verb and means a firm “have to,” it's děi; if it comes after the verb linking how the action went, it's the particle de.
The structure
Colour key
Each colour marks one grammatical role — and the same colour means the same role on every page in the Lab.
Examples in context
Real-world sentences, easiest first. Toggle pinyin or the translation, tap any word to see its role, or play the audio.
Tap a word to see its grammatical role.
wǒmen 我们 Subject děi 得 Pattern zǒu 走 Verb le 了 Function word
We have to go now (得 = děi, with the change-of-situation 了).
nǐ 你 Subject děi 得 Pattern bāng 帮 Verb tā 他 Object
You must help him (得 + verb + object).
shíjiān bù zǎo le 时间不早了 Other wǒ ，我 Subject děi 得 Pattern huíjiā 回家 Verb le 了 Function word
It's getting late, I have to head home (得 with a reason clause).
shì nǐ de cuò 是你的错 Other nǐ ，你 Subject děi 得 Pattern dàoqiàn 道歉 Verb
It's your fault, you must apologize (得 marking an obligation).
nǐ 你 Subject děi 得 Pattern xiān 先 Adverb fù qián 付钱 Verb zài 再 Adverb jìnqù 进去 Verb
You have to pay first, then go in (得 + a 先…再… sequence).
zài xuéxiào 在学校 Place jiù 就 Adverb děi 得 Pattern tīng 听 Verb lǎoshī de huà 老师的话 Object
At school you've got to listen to the teacher (就得, “then you have to”).
nǐ 你 Subject bìng 病 Verb de 得 Function word tài lìhai le 太厉害了 Complement děi ，得 Pattern qù 去 Verb kàn yīshēng 看医生 Verb
You're really sick, you must see a doctor (both 得: 病得 is de, 得去 is děi).
míngtiān qù miànshì 明天去面试 Other nǐ ，你 Subject děi 得 Pattern chuān 穿 Verb de 得 Function word zhèngshì yìdiǎn 正式一点 Complement
You must dress a bit more formally for the interview (both 得: 得穿 is děi, 穿得 is de).
Common mistakes
Why it happens: The negative of 得 (děi, “must”) is 不用 / 不必, not 不得. “You must go” 你得去 becomes 你不用去 (“you don't have to go”). 不得 (bùdé) means “must not / may not,” the opposite verdict, so it never turns “must” into “don't have to.”
Why it happens: 得 already means “must,” so you don't stack 要 on it. It's 你得道歉, not 你得要道歉. Add nothing between 得 and the verb except ordinary adverbs (得先付钱, 得马上走); the obligation is already in the 得.
Why it happens: The “must” word is the character 得 (read děi), not the possessive 的. “We have to go now” is 我们得走了, not 我们的走了 (which would read wǒmen de and mean nothing here). When 得 is the modal it's děi and comes before the verb.
Compare & contrast
| 得 (děi): “must,” auxiliary BEFORE the verb | 得 (de): particle AFTER the verb | The difference |
|---|---|---|
| 你得走了nǐ děi zǒu le = “you must go now” (得 read děi, the auxiliary, before the verb) | 你走得很快nǐ zǒu de hěn kuài = “you walk fast” (得 read de, the particle, after the verb) | 你得走了 = “you must go now,” 得 read děi, the auxiliary sitting before the verb. 你走得很快 = “you walk fast,” 得 read de, the particle sitting after the verb to link the degree. Same character, position tells you the reading. |
| 你得马上离开nǐ děi mǎshàng líkāi = “you have to leave right now” (得 = děi, must) | 他离开得很匆忙tā líkāi de hěn cōngmáng = “he left in a real hurry” (得 = de, linking the manner) | 你得马上离开 = “you have to leave right now,” 得 = děi (must). 他离开得很匆忙 = “he left in a real hurry,” 得 = de, joining the verb to how it was done. Before the verb it's “must”; after it, it's the complement particle. |
Try it yourself
Say “We have to go now.” Subject + 得 + verb phrase, and close it with 了.
Related patterns
Quick reference card
How to Say “Must” with 得 (děi) grammar.merrymandarin.com A pocket summary — print it and keep it by your desk.