difficulty 当名词时可以表示
难题,可数 a difficulty is a problem
困难 不可数 if you have difficulty doing something,your are not able to do it easily.
所有这里选 difficulty
difficulty 当名词时可以表示
难题,可数 a difficulty is a problem
困难 不可数 if you have difficulty doing something,your are not able to do it easily.
所有这里选 difficulty