matter.trouble.problem.difficulty可数,不可数

matter.trouble.problem.difficulty可数,不可数 difficulty problem trouble区别 difficulty可数与不可数 difficulty,trouble可不可数啊? trouble matter problem question trouble可数还是不可数 trouble 可数还是不可数? Problem可数还是不可数 problem.question,trouble,difficulty的区别? difficulty,trouble,problem,quesfior的区别 difficulty,problem,trouble,question的区别 1.difficulty什么时候可数,什么时候不可数