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》

We have a difficult problem to solve.

我们面临一个难以解决的问题。

youdao

How to select appropriate components to implement the design of the SOC is a difficult problem to solve.

如何选择合适的元件来实现系统芯片设计是目前面临的重大难题之一。

youdao

She began to explain to the students how to solve a very difficult problem.

VOA: special.2009.10.25

Finally, the bill has gained support among Republicans, in part because it is seen as a technological fix to a difficult to solve problem.

FORBES: Analysis: What's the Next Step for E-Verify?

We get irritated when CSRs are difficult to understand and irritated when CSRs fail to solve what ought to be a simple problem.

FORBES: It's Not the Stupid Worker...