arduous

完成这项艰巨的任务需要极大的耐心和毅力。

Completing this ___arduous task requires great patience and perseverance.

穿越积雪覆盖的山口的艰苦跋涉考验了最有经验的登山者。

The ___arduous trek through the snow-covered pass tested even the most seasoned mountaineers.

修复老教堂里那幅残破的壁画是一项极其艰苦的工作。

Restoring the crumbling fresco in the old cathedral proved an ___arduous undertaking.