difficuty的可数与不可数

difficuty 当是“困难、艰难”的意思时,不可数；当是“难点、难题、难事或异议”时，可数。

一般来说，difficulty作为抽象名词可以以复数形式出现，但是不能记数。如：opinions,sympathies等。
（以下from 金山）
【复数】 difficulties
The condition or quality of being difficult:
困难：困难的环境或程序：
the difficulty of a task.
艰巨的任务
Something not easily done, accomplished, comprehended, or solved.
难事：不容易做、完成、理解或解决的事情
Often difficulties A troublesome or embarrassing state of affairs, especially of financial affairs.
常作 difficulties 窘境：很麻烦的或窘迫的事务，特别是指经济事务
A laborious effort; a struggle; trouble:
艰难：费力的尝试；麻烦事；烦恼：
had difficulty walking; completed the test with difficulty.
行动艰难；很艰难地通过测验
A disagreement or dispute.
异议：意见不和或争执
Reluctance or an objection; unwillingness.
反对：不愿意或反对；不情愿