竟然 / 居然: surprisingly, actually
副词 / adverbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
竟然 and 居然 express the speaker's surprise at an unexpected fact: "to my surprise", "actually", "went so far as to". The fact can be good or bad.
They go after the subject, before the verb. 居然 is a bit more colloquial; 竟然 more common in writing (literary short form: 竟). Versus 不料: 不料 is a connector between clauses; 竟然 is an adverb inside a clause.
Examples
这座桥竟然已经有一千多年的历史了。
Zhè zuò qiáo jìngrán yǐjīng yǒu yìqiān duō nián de lìshǐ le.Believe it or not, this bridge is over a thousand years old.
他居然连自己国家的首都都不知道！
Tā jūrán lián zìjǐ guójiā de shǒudū dōu bù zhīdào!He actually doesn't even know his own country's capital!
一个农民竟然当上了皇帝。
Yí ge nóngmín jìngrán dāng shàng le huángdì.A peasant actually became emperor.
Common mistakes
✗ 竟然他… → ✓ 他竟然… (after the subject).
✗ 竟然 for something planned: ✗ 我竟然按计划去了 → there must be real surprise.
✗ 竟然 + 吗: ✗ 他竟然来了吗？ → ✓ 他竟然来了！