That's a hard / difficult question.

那是难以回答的问题。

youdao

It is hard (difficult) for him to teach English.

对他来说，教英语是件力不从心的事。

youdao

The main subjects for ceramic machining researches include the hard-difficult machining theory, the grinding mechanism, precision grinding and high efficiency grinding.

包括工程陶瓷材料难加工的理论基础研究，磨削机理，超精密磨削，高效磨削加工等方面的研究动态。

youdao

We slept on the hard ground, ate canned beans from cold metal plates and spent our days in the difficult search for gold.

VOA: special.2009.07.04

But,it's hard,if you're fourty-seven years, your job is a pretender to the throne, it's difficult.He had a hard time getting around.

但是,如果你要花四十七年,去争夺王位,是很不容易的,他做得很艰苦

耶鲁公开课 - 1871年后的法国课程节选

Why has it been so hard and why does it continue to be difficult to identify these pluripotent cells within tissues?

为什么会那么难呢,为什么在组织中识别多能干细胞,始终困难重重呢

耶鲁公开课 - 生物医学工程探索课程节选

I've learned a hard and difficult lesson considering the childhood environment that I was brought up in - not to discriminate against any plant or creature.

BBC: Norfolk - Chris Skinner's wildlife haven

One reason for doubt about the overall efficacy of rewards, Natapoff says, is that hard data is difficult to come by.

FORBES: Magazine Article

These are rugged mountains in the Sinai close to the coastline, mountains with difficult, hard to find paths.

NPR: Suicide Bombers Hit International Force in Sinai