n.[C]

1. 问题，疑难问题
   Measures have been taken to solve traffic problems in big cities.

   业已采取措施以解决大城市的交通问题。

2. 【数】习题，几何作图题
3. 难弄的人，引起麻烦的人[S1]
   My kid brother is a real problem.

   我弟弟真是个难弄的人。

n.

1. an unwelcome or harmful matter needing to be dealt with and overcome.
   ▸a thing that is difficult to achieve.
2. Physics  & Mathematics  an inquiry starting from given conditions to investigate or demonstrate something.
3. (in chess) an arrangement of pieces in which the solver has to achieve a specified result.