分明: plainly, evidently (against what follows)
【高35】副词 / adverbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
分明 says that something is plainly so, usually to set it against a statement or behaviour that contradicts it: "clearly, quite evidently (and yet…)". It carries surprise or accusation, and almost always calls for a second half with 却, 怎么, 可 or 还: 我分明看见他走过来了，怎么一下子就不见了呢？; 让我三天就完成，你分明是在为难我.
Compared with its neighbours, 分明 is more literary than 明明 (more usual in speech) and more charged than 显然 or 明显, which note an obvious fact without opposing anything. If the sentence has no contrast and no reproach, use 显然.
This page teaches the mood adverb, "plainly". 分明 is also an adjective, "clear, distinct" (黑白分明), which is a different use.
Examples
他分明很高兴，却说不想去。
Tā fēnmíng hěn gāoxìng, què shuō bù xiǎng qù.He is plainly delighted, yet he says he does not want to go.
你分明答应过我，现在怎么又说不行了？
Nǐ fēnmíng dāying guo wǒ, xiànzài zěnme yòu shuō bù xíng le?You clearly promised me, so how can you say no now?
我分明看见他走过来了，怎么一下子就不见了呢？
Wǒ fēnmíng kànjiàn tā zǒu guòlái le, zěnme yíxiàzi jiù bú jiàn le ne?I clearly saw him walking over, so how did he vanish all at once?
让我三天就完成，你分明是在为难我。
Ràng wǒ sān tiān jiù wánchéng, nǐ fēnmíng shì zài wéinán wǒ.Asking me to finish in three days, you are plainly trying to make things hard for me.
那条路我分明走过很多遍，可今天怎么也找不到了。
Nà tiáo lù wǒ fēnmíng zǒu guo hěn duō biàn, kě jīntiān zěnme yě zhǎo bu dào le.I have walked that road many times, yet today I simply cannot find it.
她分明在笑，眼里却含着泪。
Tā fēnmíng zài xiào, yǎn li què hán zhe lèi.She is plainly smiling, yet her eyes are full of tears.
Common mistakes
✗ 这个办法分明很有用 → ✓ 这个办法显然很有用 (分明 sets a fact against what contradicts it; with no contrast, 显然 is the neutral choice).
✗ 他分明很高兴，所以说不想去 → ✓ 他分明很高兴，却说不想去 (the second half contradicts the first, it is not a consequence).