difficult of难以, 很难
difficultadj.困难的;艰难的;(人)难对付的;不易相处的
difficult biodegradation难生物降解
difficult in the extreme极其艰苦
difficult criminal cases疑难刑事案件
difficulties in teaching教学难点
difficultly washabe coal难选煤
difficult to raise funds融资难
difficult of explanation难以解释
difficult to machine job难于在机器上加工的工件
difficulties and problems难点与问题
difficulties of financing融资难