difficult可数吗

difficult是形容词，不是名词，所以不存在可数和不可数的概念。
短语：
Difficult to predict 难以预料 ; 难测
Difficult to find 难觅 ; 敌手难觅 ; 难以找到
Difficult to predict heart 人心难测

例句：

The exam was quite difficult、

这场考试相当难。

The exam was fairly difficult、

这场考试相当难。

The exam was pretty difficult、

这场考试相当难。