连 + Extreme example + 都/也 + (不/没) + Verb
连...都/也... (lián...dōu/yě...) — 'even...'
连 fronts an extreme or surprising example — the least likely case — and 都 or 也 right after it emphasizes 'even this counts': 连小孩儿都懂 (even a small child understands [this] — so it must be really simple), 他连一句话都没说 (he didn't even say a single word). The example after 连 is usually the most extreme point on some scale (the youngest, the smallest amount, the easiest task) to make the claim about everything else even stronger by implication. 都 and 也 are largely interchangeable here; 都 is slightly more common. The deciding question: am I picking the single most surprising/extreme case to prove a broader point applies to everything else too? If so, front it with 连 and follow with 都/也 — a bare 都 or 也 without 连 loses that 'even' emphasis and just becomes a plain 'all/also' statement.
Examples
- 这个问题连小孩儿都懂。zhè ge wèn tí lián xiǎo háir dōu dǒng
Even a small child understands this question.
- 他连一句话都没说就走了。tā lián yí jù huà dōu méi shuō jiù zǒu le
He left without even saying a single word.
- 这道题太难了，连老师也不知道怎么解。zhè dào tí tài nán le, lián lǎo shī yě bù zhī dào zěn me jiě
This problem is so hard that even the teacher doesn't know how to solve it.
Common mistake
✗ Wrong: 他连一句话没说就走了。
✓ Right: 他连一句话都没说就走了。
连 needs 都 or 也 right after the extreme example to complete the 'even' emphasis — 连 alone, without 都/也, is left hanging.
Practice this pattern
Fill in the missing character:
这个问题＿小孩儿都懂。
Even a small child understands this question.