difficulty 通常是不可数名词；difficulty 前可用 some，any，no，great，much，little等修饰；
复数： difficulties
The tasks have been ranked in order of difficulty.
按照困难程度对工作进行了分类。
Many clubs in the lower reaches of the league are in financial difficulty.
联盟下层的许多俱乐部都处于财政困难之中。
The difficulty of a problem was defined in terms of how long it took to complete.
问题的难易度是以解决这个问题所花时间的长短而定的。
温馨提示：
