V + 得 / 不 + complement — built-in 'can' and 'can't'
Mandarin has THREE different ways to say 'can': 能 (situational possibility), 会 (acquired skill), and the potential complement V + 得 + C with negative V + 不 + C. The potential complement is the most idiomatic of the three — it asks whether the result of a specific action can be ACHIEVED. 看得懂 = can understand (when reading). 看不懂 = can't understand. 吃得完 = can finish eating it. 吃不完 = can't finish eating it. 听得见 = can hear. 听不见 = can't hear. The pattern is just V + 得 + C for can, V + 不 + C for can't — same compound as the resultative, with 得 or 不 wedged in between. In speech, V不C is much more common than V得C — Mandarin speakers ask 'can you?' more often than asserting 'I can'.
The shape — slot 得 or 不 between V and C
Take any V + complement compound from lesson 17 / 26 — say 看懂. To make 'can' or 'can't', wedge 得 de (neutral tone) or 不 bù between the two characters. Positive: 看得懂 = can understand. Negative: 看不懂 = can't understand. Same with 听懂 → 听得懂 / 听不懂. 吃完 → 吃得完 / 吃不完. 找到 → 找得到 / 找不到. 看见 → 看得见 / 看不见. Crucially, the three pieces are written and spoken as one tight unit, like kàn-de-dǒng, with 得 at neutral tone. 得 here is a different word from possessive 的 (lesson 4) and from descriptive 得 in V得 + adjective (which we'll see for manner).
The negative is the high-frequency form — V不C
In real conversation, V不C wildly outranks V得C in frequency. Speakers most often disclaim ability ('I can't quite ...') rather than assert it. Top everyday examples: 看不懂 (can't make out the meaning), 听不懂 (can't catch what's said), 听不见 (can't hear — too far / too loud), 看不见 (can't see — blocked / too dark), 找不到 (can't find), 想不起来 (can't recall — lesson 27), 吃不完 (can't finish — too much food), 写不完 (can't finish writing — too long), 来不及 (can't make it in time — fixed phrase). Memorize these as units.
Questions — V得C 吗 or V得C V不C
Two natural ways to ask 'can you?'. (1) V得C 吗 — straightforward yes-no: 你看得懂吗? = Can you understand it? (2) The signature V-not-V flavor for potentials, V得C V不C: 你看得懂看不懂? = Can you understand or not? — fully spelled out. (3) A shorter colloquial trim: V得V不得 + C is not standard; stick to (1) and (2). Short answers can echo the form: 'Q: 你看得懂吗? A: 看得懂。 / 看不懂。' Short answers don't repeat the subject — just give back the V得C or V不C unit.
得 vs. 了 — potential vs. completed
Critical contrast. V得C = ABILITY in general (can the result be achieved?). V完了 / V懂了 / V到了 = completed action (the result WAS achieved this time). 我看得懂这本书。 = I can read (understand) this book — talking about ability. 我看懂了这本书。 = I (have) understood this book — talking about a completed event. The negatives split the same way: 看不懂 = can't (general). 没看懂 = didn't (this time). 'I can't read your handwriting' = 我看不懂你的字。 vs. 'I didn't catch what you said' = 我没听懂。 Both are common; mixing them up is a classic learner error.
Potential complement vs. 能 — overlap and difference
Both 能 (lesson 13) and V得C can be glossed 'can', but they cover different territory. 能 = general possibility / permission / external circumstance allows it. V得C = the action's RESULT can be achieved (often about inner capability or environmental success of the outcome). Overlap zone: 我听不懂 ≈ 我不能听懂 in meaning, but the second is awkward — Mandarin strongly prefers 听不懂 for inability to comprehend. 我能进去吗? = Can I go in? (asking permission — use 能). 门坏了,我进不去。 = The door's broken, I can't get in (the result fails — use V不C). Rule of thumb: if the question is about permission or external possibility, use 能. If the question is about whether the action's RESULT will succeed, use V得C / V不C. With sensory and comprehension complements (懂, 见, 到), V得C is heavily preferred over 能.
得了 / 不了 — a high-frequency wildcard complement
了 liǎo (third tone, written 了 — same character as the perfective particle) is a special complement meaning 'be able to bring it off / can manage'. V得了 = able to manage (to do/finish/handle). V不了 = unable. 我吃不了这么多。 = I can't manage to eat this much. 明天我去不了。 = I can't make it tomorrow. 这件事我办得了。 = I can handle this matter. Watch out: 了 here is liǎo (verb 'to finish / be able'), NOT le (the perfective particle). Pinyin and tone are different even though the character is the same. 来不了 = can't come. 去不了 = can't go. 办不了 = can't handle it. These are extremely common — learn them as units alongside 看不懂, 找不到, etc.
