The term 'mental illness' is difficult to define.

“精神病”这个词很难下定义。

《牛津词典》

The promise of finding long-term technological solutions to the problem of world food shortages seems difficult to fulfill.

为世界粮食短缺问题找到长期技术解决方案的希望似乎很难实现。

youdao

Determining the functions of play is difficult because the functions may be long-term, with beneficial effects not showing up until the animal's adulthood.

定义玩耍的功能是困难的，因为这些功能可能是长期性的，其积极影响要到动物成年后才会显现。

youdao

Interesting. Even though the market seized up very dramatically afterwards and we had some of the most difficult short-term financial consequences of that failure?

有意思，尽管市场严重失灵,我们面临着,许多短期的,非常严重的后果？

斯坦福公开课 - 经济学课程节选

Many Americans in border states support cracking down on illegal migrants, and Mr Obama's Democratic Party faces difficult mid-term elections in November.

ECONOMIST: Mexico and the United States: An unappetising menu | The

Of course, ignoring short term swings up or down is difficult but required for long term financial success.

FORBES: Regaining Control in a Crazy Market

He explained NIE's short, medium and long term plans but said it would be difficult to get beyond the medium term targets without further infrastructure in the west.

BBC: Enterprise Committee