明明: clearly, plainly (and yet)
【五08】语气副词 / adverbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
明明 (“clearly, plainly”) states something obvious, then the sentence shows a reaction that ignores or contradicts it: 明明是你做的，为什么说不是？ (it was plainly you who did it, so why say it wasn't?). The speaker is annoyed, puzzled or accusing.
So it needs a second part that clashes with the first, often introduced by 却 (hsk3-g30), 还 or 为什么, or a question. Without that clash, 明明 has no job to do. It goes after the subject, or at the head of the sentence.
Do not mix it up with 其实 (hsk3-g50), a neutral “actually”, or with 竟然 / 居然 (hsk5-g32), which express surprise at an unexpected fact. 明明 is not surprised at the fact itself: it reproaches or wonders at a contradiction.
Examples
他明明很累，却不愿意休息。
Tā míngmíng hěn lèi, què bú yuànyì xiūxi.He is plainly exhausted, yet he won't rest.
你明明知道答案，为什么不说？
Nǐ míngmíng zhīdào dáàn, wèishénme bù shuō?You clearly know the answer, so why don't you say it?
这道题明明很简单，你为什么做错了？
Zhè dào tí míngmíng hěn jiǎndān, nǐ wèishénme zuò cuò le?This question is plainly easy, so why did you get it wrong?
明明是你说要去的，现在怎么又不去了？
Míngmíng shì nǐ shuō yào qù de, xiànzài zěnme yòu bú qù le?You were the one who said you wanted to go, so why are you backing out now?
我明明记得把手机放在桌子上了，怎么找不到了？
Wǒ míngmíng jìde bǎ shǒujī fàng zài zhuōzi shang le, zěnme zhǎo bu dào le?I distinctly remember putting my phone on the table, so how come I can't find it?
她明明很喜欢这份工作，却还是决定辞职。
Tā míngmíng hěn xǐhuan zhè fèn gōngzuò, què háishi juédìng cízhí.She obviously loves this job, yet she decided to resign.
Common mistakes
✗ 他明明很累，所以他睡了 → ✓ 他明明很累，却不愿意睡 (明明 calls for a clash, not a logical result).
✗ 他明明会不会说中文？ → ✓ 他明明会说中文，为什么不说？ (明明 asserts an obvious fact, so it does not fit a real question).