Mandarin Potential Complements: Can You Reach the Result? (吃得完, 听不懂, 买不起)

The principle: possibility baked into the verb

You already have resultative complements (verb + result, like 看见 (kàn jiàn) see, 吃完 (chī wán) finish eating) and directional complements (verb + direction, like 进去 (jìn qù) go in, 起来 (qǐ lái) get up). The potential complement is built directly from them. You take that fused verb-result unit and split it with a tiny infix:

• 得 (de) in the middle = the result CAN be reached.
• 不 (bù, here neutral-toned bu) in the middle = the result CANNOT be reached.

verb + 得dé (de)/不bù (bù) + result

• 吃得dé完 (chī de wán) - can finish eating
• 吃不bù完 (chī bu wán) - cannot finish eating (too much food)
• 看得dé见 (kàn de jiàn) - can see / can make out
• 看不bù见 (kàn bu jiàn) - cannot see
• 听得dé懂 (tīng de dǒng) - can understand (by listening)
• 听不bù懂 (tīng bu dǒng) - cannot understand
• 做得dé到 (zuò de dào) - can manage it / can pull it off
• 做不bù到 (zuò bu dào) - cannot manage it

Notice the shape. 看见 (kàn jiàn) is the plain resultative ('saw'). Insert 得 (de) and you get 看得见 ('can see'); insert 不 (bù) and you get 看不见 ('can't see'). The verb and the result stay the same; only the seam changes.

The negative 不 (bù) form is the everyday workhorse

Here is the single most useful fact about this pattern: in real speech the NEGATIVE (不 (bù)) form is far more common than the affirmative (得 (de)) form. People are forever saying they can't finish, can't see, can't hear, can't afford, can't understand. The 不 (bù) versions are everywhere.

• 这么多菜，我们吃不bù完。 (Zhè me duō cài, wǒ men chī bu wán.) - There's so much food, we can't finish it.
• 太远了，我看不bù见。 (Tài yuǎn le, wǒ kàn bu jiàn.) - It's too far, I can't see it.
• 你说得太快，我听不bù懂。 (Nǐ shuō de tài kuài, wǒ tīng bu dǒng.) - You speak too fast, I can't understand.
• 这个房子我买不bù起。 (Zhè ge fáng zi wǒ mǎi bu qǐ.) - I can't afford this house.

The affirmative 得 (de) form does exist and is correct, but in conversation it most often appears as the answer to a question, or for contrast and reassurance.

• 听得dé懂吗？听得dé懂。 (Tīng de dǒng ma? Tīng de dǒng.) - Can you understand? Yes, I can.
• 别担心，我们吃得dé完。 (Bié dān xīn, wǒ men chī de wán.) - Don't worry, we can finish it.

Drill the negatives until they are automatic. They will carry most of your real-world usage.

买得起 (mǎi de qǐ) / 买不起 (mǎi bù qǐ): the 'afford' family

A handful of potential complements have meanings you would never guess from the parts, and 起 (qǐ) is the classic. Built onto a verb it asks whether you can bear the cost - usually money, sometimes effort or social standing.

• 买得dé起 (mǎi de qǐ) - can afford to buy
• 买不bù起 (mǎi bu qǐ) - cannot afford to buy
• 住不bù起 (zhù bu qǐ) - cannot afford to live (somewhere)
• 看不bù起 (kàn bu qǐ) - to look down on, to despise (idiomatic; 'cannot regard as worth looking at')

Watch 看不起 (kàn bù qǐ). It is not 'cannot see' - that is 看不见 (kàn bú jiàn). 看不起 (kàn bù qǐ) means to hold someone in contempt. The 起 (qǐ) morpheme has carried the meaning a long way from the literal.

Potential complement versus 能 (néng) / 可以 (kě yǐ)

This is the distinction that separates intermediate learners from beginners. Both the potential complement and the modal verbs 能 (néng) / 可以 (kěyǐ) translate as English 'can', but they cover different ground.

• The potential complement is about the INHERENT possibility of the action reaching its result. Is it physically or practically achievable? Is the food finishable, the sound audible, the writing legible, the price affordable? It lives in the verb-result relationship itself.
• 能néng / 可kě以yǐ lean towards circumstance and permission. Are you allowed to? Is it possible given the situation? Is the road clear, is it your turn, do the rules permit it?

Often both are grammatical and the difference is one of emphasis. 我看不懂 (wǒ kàn bù dǒng) and 我不能看懂 (wǒ bù néng kàn dǒng) are both possible, but the first (potential complement) is overwhelmingly the natural spoken choice; the second sounds heavy and bookish. As a rule of thumb: if the 'can' is about whether the action lands its result, prefer the potential complement; if it is about permission or external circumstance, reach for 能 (néng) or 可以 (kě yǐ).

One firm restriction: the potential complement cannot stack with 能 (néng) in the affirmative. ✗ 我能看得懂 (wǒ néng kàn de dǒng) is clumsy. Say 我看得懂 (wǒ kàn de dǒng) or 我能看懂 (wǒ néng kàn dǒng). Keep them apart.

NOT the same as the 得 (de) manner complement

This is the trap that catches almost everyone, because the two patterns share the character 得 (de) and look identical on the page.

• Potential complement: verb + 得 + RESULT. The 得 sits between the verb and a result/direction morpheme, and the whole thing is about possibility. 跑得dé动 (pǎo de dòng) - can run / am able to keep running.
• Manner complement (also called the degree complement): verb + 得 + DESCRIPTION. The 得 introduces a description of HOW the action is performed. 跑得dé快 (pǎo de kuài) - runs fast / runs quickly.

Same 得 (de), completely different jobs. 跑得动 (pǎo de dòng) is about whether you are physically able to run. 跑得快 (pǎo de kuài) is a comment on the manner - the running is fast. The tell is what follows 得 (de): a result/direction morpheme (动 (dòng), 完 (wán), 懂 (dǒng), 见 (jiàn)) signals a potential complement; an adjective or descriptive phrase (快 (kuài), 很好 (hěn hǎo), 很流利 (hěn liú lì)) signals a manner complement.

• 他汉语说得dé很流利。 (Tā hàn yǔ shuō de hěn liú lì.) - He speaks Chinese very fluently. (Manner: how he speaks.)
• 他的汉语我听得dé懂。 (Tā de hàn yǔ wǒ tīng de dǒng.) - I can understand his Chinese. (Potential: whether I can.)

And the negatives diverge completely, which is the clincher. The manner complement negates inside the description (跑得不快 (pǎo de bú kuài), 'doesn't run fast'). The potential complement negates by swapping 得 (de) for 不 (跑不动 (pǎo bú dòng), 'can't run'). If you can replace 得 (de) with 不 (bù) to flip the meaning to 'can't', you are looking at a potential complement. See the complements overview for the manner pattern in full.

The question form: V得 (de)V不 (bù) and ...得了吗 (dé le ma)

To ask whether something can reach its result, you have two natural shapes.

Shape 1: the affirmative-negative question, V得dé (de) ... V不bù (bù) ...

Lay the positive and negative potentials side by side, exactly like the 是不是 (shì bu shì) / 去不去 (qù bu qù) verb-not-verb question.

• 你听得dé懂dǒng听tīng不bù懂dǒng？ (Nǐ tīng de dǒng tīng bu dǒng?) - Can you understand or not?
• 这些菜你吃得dé完wán吃chī不bù完wán？ (Zhè xiē cài nǐ chī de wán chī bu wán?) - Can you finish all this food?

Shape 2: the plain 吗ma (ma) question on the affirmative form

• 你听得dé懂dǒng吗？ (Nǐ tīng de dǒng ma?) - Can you understand?
• 今天做得dé完wán吗？ (Jīn tiān zuò de wán ma?) - Can it get finished today?

A special, very common result morpheme here is 了 (liǎo, NOT le), meaning roughly 'be able to bring off'. It pairs with all sorts of verbs to ask broad capability.

• 你来得dé了le吗？ (Nǐ lái de liǎo ma?) - Will you be able to come?
• 这么多饭我吃不bù了le。 (Zhè me duō fàn wǒ chī bu liǎo.) - I can't eat all this food.
• 这点小事，我受得dé了le。 (Zhè diǎn xiǎo shì, wǒ shòu de liǎo.) - A small thing like this, I can take it.

Note that 吃不完 (chī bù wán) and 吃不了 (chī bù liǎo) overlap but differ in shade: 吃不完 (chī bù wán) = can't finish (too much to get through); 吃不了 (chī bù liǎo) = can't manage to eat it (can't bring it off at all, perhaps no appetite, perhaps too much).

Fixed items worth memorising whole

Several potential complements have hardened into set expressions used far beyond their literal parts. Learn these as vocabulary.

• 受不bù了 (shòu bu liǎo) - can't stand it / can't bear it. 这么热，我受不了。 (Zhè me rè, wǒ shòu bu liǎo.) - It's so hot, I can't stand it.
• 来不bù及 (lái bu jí) - there isn't time / too late to make it. 快点，要来不及了！ (Kuài diǎn, yào lái bu jí le!) - Hurry, we're going to be late! Its positive twin 来得及 (lái de jí) = there's still time.
• 划得dé来 (huá de lái) - worth it / a good deal, and 划不bù来 (huá bu lái) - not worth it. 这么贵，划不来。 (Zhè me guì, huá bu lái.) - That expensive, it's not worth it.
• 怪不bù得 (guài bu de) - no wonder / that explains it. 怪不得他不来，原来病了。 (Guài bu de tā bù lái, yuán lái bìng le.) - No wonder he isn't coming, turns out he's ill.
• 巴不bù得 (bā bu de) - to be only too eager, to wish desperately. 我巴不得马上放假。 (Wǒ bā bu de mǎ shàng fàng jià.) - I can't wait for the holidays to start.
• 恨不bù得 (hèn bu de) - to wish one could (but can't), often hyperbolic. 我恨不得马上飞过去。 (Wǒ hèn bu de mǎ shàng fēi guò qù.) - I wish I could fly over there right now.

These do not all behave like regular potential complements - 怪不得 (guài bù de), 巴不得 (bā bù de) and 恨不得 (hèn bù de) in particular have drifted into fixed idioms with no live 得 (de) counterpart in everyday use. Treat them as set phrases rather than productive patterns.

Worked examples

• 字太小了，我看不bù清楚。 (Zì tài xiǎo le, wǒ kàn bu qīng chu.) - The print is too small, I can't see it clearly.
• 这个道理你想得dé通吗？ (Zhè ge dào lǐ nǐ xiǎng de tōng ma?) - Can you get your head round this?
• 行李太重，我拿不bù动。 (Xíng li tài zhòng, wǒ ná bu dòng.) - The luggage is too heavy, I can't lift it.
• 这道题我做得dé出来。 (Zhè dào tí wǒ zuò de chū lái.) - I can work this problem out.
• 时间还早，我们赶得dé上火车。 (Shí jiān hái zǎo, wǒ men gǎn de shàng huǒ chē.) - There's still time, we can catch the train.
• 他的口音我实在听不bù惯。 (Tā de kǒu yīn wǒ shí zài tīng bu guàn.) - I just can't get used to his accent.

Common mistakes

1. Reaching for 能néng (néng) by reflex. For 'I can't understand him', the natural Chinese is 我听不懂他 (wǒ tīng bù dǒng tā), not 我不能懂他 (wǒ bù néng dǒng tā). Default to the potential complement when the 'can' is about reaching a result.
2. Confusing the two 得dé (de)s. 跑得快 (pǎo de kuài) is manner ('runs fast'); 跑得动 (pǎo de dòng) is potential ('can run'). Check what follows 得 (de).
3. Negating the potential complement with 没méi (méi). ✗ 我没看懂 (wǒ méi kàn dǒng) is a different sentence (resultative: 'didn't understand it that time'). The potential negative is 看不懂 ('can't understand it at all'). 没看懂 (méi kàn dǒng) = didn't; 看不懂 (kàn bù dǒng) = can't.
4. Stacking 能néng (néng) onto the affirmative. ✗ 我能听得懂 (wǒ néng tīng de dǒng). Pick one: 我听得懂 (wǒ tīng de dǒng) or 我能听懂 (wǒ néng tīng dǒng).
5. Splitting 起qǐ (qǐ) the wrong way. 看不起 (kàn bù qǐ) is 'despise', not 'cannot see'. 'Cannot see' is 看不见 (kàn bú jiàn).

What to drill

1. Build it from the resultative. Take 吃完 (chī wán), 听懂 (tīng dǒng), 看见 (kàn jiàn), 买起 (mǎi qǐ), then split with 得 (de) or 不 (bù): 吃得完 (chī de wán)/吃不完 (chī bù wán).
2. Lead with the negatives. 吃不完 (chī bù wán), 听不懂 (tīng bù dǒng), 买不起 (mǎi bù qǐ), 看不见 (kàn bú jiàn) carry most real speech.
3. Keep potential and manner apart. Result/direction after 得 (de) = possibility; adjective after 得 (de) = manner.
4. Use 不bù (bù), not 没méi (méi), to say 'can't'. 听不懂 (tīng bù dǒng) = can't understand; 没听懂 (méi tīng dǒng) = didn't understand.
5. Memorise the set phrases whole. 受不了 (shòu bù liǎo), 来不及 (lái bù jí), 来得及 (lái de jí), 划不来 (huá bù lái), 怪不得 (guài bù de), 巴不得 (bā bù de).

This pattern is built straight on top of two others, so make sure those are solid first. For the verb-plus-result units that supply the affirmative meaning, see resultative complements. For the direction morphemes (进 (jìn), 出 (chū), 起来 (qǐ lái), 过去 (guò qù)) that also feed potential complements, and the look-alike 得 (de) that describes manner rather than possibility, see the wider family of verb endings on the complements overview.