challenge

Climbing Mount Everest remains the ultimate physical challenge for many adventurers.

(Chinese) 攀登珠穆朗玛峰仍然是许多探险家面临的终极体能挑战。

Finding a cure for this rare disease is a major challenge for modern medicine.

(Chinese) 寻找这种罕见病的治疗方法是现代医学面临的一大挑战。

The young grandmaster decided to challenge the world champion to a chess match.

(Chinese) 年轻的大师决定向世界冠军发起国际象棋比赛的挑战。

The defense lawyer tried to challenge the witness's memory of the events.

(Chinese) 辩方律师试图对证人对事件的回忆提出质疑（挑战其准确性）。