却 (què) adds a "yet, contrary to what you'd expect" flavor to the second half of a sentence: 我等了他一个小时,他却没来 "I waited an hour for him, yet he didn't come".
The trap: 却 is an ADVERB, not a conjunction. It sits after the subject, before the verb — it can never start the clause the way 但是 does. The two happily team up: 但是他却没来 (但是 opens the clause, 却 stays by the verb).
Examples
我等了他一个小时,他却没来。
我等了他一個小時,他卻沒來。
wǒ děng le tā yī ge xiǎo shí tā què méi lái
I waited an hour for him, yet he didn't come.
这个东西很便宜,却很好用。
這個東西很便宜,卻很好用。
zhè ge dōng xi hěn pián yi què hěn hǎo yòng
This thing is cheap, yet it works really well.
他学了三年中文,却不敢说。
他學了三年中文,卻不敢說。
tā xué le sān nián zhōng wén què bù gǎn shuō
He studied Chinese for three years, yet he doesn't dare speak.
大家都同意,他却反对。
大家都同意,他卻反對。
dà jiā dōu tóng yì tā què fǎn duì
Everyone agrees, yet he's against it.
Common mistakes
✗ 我想去,却他不想去。
✓ 我想去,他却不想去。
却 comes after the subject, before the verb — it can't open the clause like 但是.
Every grammar point in this guide is built into the Literate Chinese app, with graded stories that use the pattern naturally and flashcards matched to the words you know — in Mainland or Taiwan Mandarin. Free on iOS and Android.