In itself, it's not a difficult problem to solve.

这本身并不是个难解决的问题。

《牛津词典》

How to improve the quality of products was a difficult problem to him.

如何提高产品质量对他来说可是个难题。

youdao

She is working at a difficult problem in mathematics.

她在做一道数学难题。

《新英汉大辞典》

But for people who have a difficult time controlling their movements, this little navigational issue can be a really big problem.

VOA: special.2011.04.18

It's a difficult problem that not everyone is smart -they vary in their ability -so we try to make a world in which it's pretty safe for the small investor who's not paying attention.

不是所有人都是聪明人,这是个难题,大家能力不同,所以我们试图营造一个环境,一个让小投资者感到安全的环境,而无需忧心忡忡

耶鲁公开课 - 金融市场课程节选

It shouldn't be difficult to see a kind of problem that is beginning to arise in Milton's text here.

这是一个很容易看出的问题,在弥尔顿的作品中也被提了出来。

耶鲁公开课 - 弥尔顿课程节选

Each one of these is a difficult problem to unwind, and many of us struggle with more than one.

FORBES: Mailbox App Revolutionizes Gmail Productivity, Will Google (Or Apple) Buy It?

Present a difficult problem, they provide a clear, direct, and preposterously simplistic answer.

FORBES: Forget Bulls And Bears: Why Are So Many Investors Boors?

We had a technology company come to us some time ago, before the tech bubble burst, with a difficult problem.

FORBES: Financial Analysts: Writing Research That Benefits Their Employers and Themselves (August 1, 2001)