快

快 (kuài) primarily means 'fast / quick' as an adjective: 他跑得很快 ('he runs very fast'), 这辆车很快 ('this car is fast'). Two extensions are everyday: (1) 'soon / about to' as an adverb signaling imminent time — 快到了 ('almost there'), 快下雨了 ('it's about to rain'), often paired with 了 at the end; (2) 'hurry up!' as an imperative — 快来 ('come quickly'), 快走 ('hurry, let's go'). In speed comparisons it pairs naturally with 慢 (màn, 'slow'): 快 / 慢. As a verb complement it follows 得: 跑得快 ('runs fast'), 学得快 ('learns quickly'). 快 is also a feeling-word in 愉快 (yúkuài, 'pleasant') and 快乐 (kuàilè, 'happy') — happiness in Chinese is associated with the briskness of 快. Don't confuse with the homophone 块 (kuài), the measure word for money and a piece of something. The phrase 快快 (reduplicated) means 'quickly, quickly' for urgency: 快快走 ('hurry, hurry, go!').

Memory hook: Heart radical 忄 + 夬 — a 'decisive heart,' acting quickly. The same 快 is in 快乐 (happy) — being happy is acting freely and quickly with the heart.

快 appears in 1 podcast episode at natural native speed, with full Chinese script, pinyin, and line-by-line English translation.