difficult的名词为difficulty，表示抽象困难时为不可数名词，表示具体的难题、难点等意思时为可数名词，其复数形式为difficulties。例如“in difficulty”的意思是处境困难；“with difficulty”的意思是艰难地；“difficulty index”的意思为难度指数、困难度指标；“have difficulty”的意思是有困难。

相关例句：1、His increasing financial difficulties forced him to take desperate measures.

不断增加的经济困难迫使他采取了铤而走险的办法。

2、Scientists have tended to skate over the difficulties of explaining dreams

科学家们往往回避释梦的难题。

3、His book presents a new approach to the difficulty.

他的书对于该项难题提出新的处理方法。

4、I've had some difficulties,but they were nothing compared to yours.

我遇到了一些困难，但与你的困难比起来就算不上什么了。

5、One of the staff saw he was in difficulty and came to his aid.

一名工作人员见他有困难，便过来帮忙。