2 sentences for 苦练 (kǔ​liàn — train hard)

1. 他为了比赛每天苦练书法。

   tā wèi le bǐ​sài měi tiān kǔ​liàn shū​fǎ.

   He practices calligraphy hard every day for the competition.

   Source: Dong Chinese Dictionary

2. 为了练就这一手厨艺绝技，他苦练了整整十年。

   wèi​le liàn​jiù zhè yī​shǒu chú​yì jué​jì, tā kǔ​liàn le zhěng​zhěng shí nián.

   In order to master this culinary skill, he practiced hard for ten whole years.

   Source: Dong Chinese Dictionary