高难 (gāo nán) — very difficult; extremely challenging

Definition

Examples

• 这个任务非常高难，需要很多时间。
  Zhè ge rèn wu fēi cháng gāo nán, xū yào hěn duō shí jiān.
  This task is very difficult and requires a lot of time.
• 这道数学题太高难了，我解不出来。
  Zhè dào shù xué tí tài gāo nán le, wǒ jiě bù chū lái.
  This math problem is too difficult; I can't solve it.
• 他面对的是一个高难的挑战。
  Tā miàn duì de shì yí gè gāo nán de tiǎo zhàn.
  He is facing a very difficult challenge.