a.

1. （指任务）需要精力或技术的；困难的[+to-v]
   It's very difficult to swim across the Yangtze River.

   游过长江很难。

   Mathematics is difficult for some students.

   有些学生觉得数学困难。

2. 难相处的，不随和的
   Mary was a very difficult child.

   玛丽过去是一个很难弄的孩子。

3. 艰难的，难熬的
   The most difficult days are over.

   最困难的日子已经过去了。

adj.

1. needing much effort or skill to accomplish, deal with, or understand.
2. not easy to please or satisfy; awkward.