就 / 才
就: early/quick/easy; 才: late/slow/difficult
HSK 3HSK 3.0 · 3
Time/condition + 就 + V (+ 了) | Time/condition + 才 + V
Both precede the verb but show opposite attitudes. 就 means earlier, faster or easier than expected (他七点就到了 'he was already here at seven'), and usually comes with 了. 才 means later, slower or harder than expected (他九点才到 'he didn't arrive until nine'), and 才 sentences do not take final 了. 才 + a number also means 'only': 才五块钱.
HSK 3–5 listening (who was early/late) and gap fills; a classic trap.
Examples
他七点就到了，我九点才到。
He got here at seven; I didn't arrive until nine.
这个问题我想了很久才明白。
It took me a long time to understand this problem.
从这儿走路五分钟就到了。
It's only a five-minute walk from here.
我等了一个小时，他才来。
I waited an hour before he finally came.
这件衣服才五十块钱，太便宜了！
This is only fifty yuan — so cheap!
Exercises
1.电影七点开始，他七点半 来。
2.Choose the correct sentence:
3.他很聪明，老师说一遍他 懂了。
4.这本书 二十块钱，不贵。