1. concerned作前置定语，含义是“不安的，忧郁的，忧心忡忡的，焦虑不安的；关心的；关切的”：
a phone call from a concerned neighbor.
不安的邻居打来的电话
the concerned educators 忧心忡忡的教育者们
Concerned parents held a meeting.
忧心忡忡的家长们开了一次会。
The concerned mother stood at the gate, waiting for her son to come back home.
焦虑不安的母亲站在大门口，等待儿子回来。
Not until the 1980's did some concerned citizens in Beijing started to find ways to preserve historical buildings from destruction.
直到20世纪80年代，北京一些忧心忡忡的市民才开始寻找保护历史建筑免遭破坏的方法。
2. concerned作后置定语，含义是“有关的，相关的” （involved）
the problems concerned 有关的问题
It's a very stressful situation for everyone concerned.
对所有相关人士来说，这一形势非常紧张。
The new regulations will be of benefit to everyone concerned.
新规章将使所有有关人员受益。
This agreement will be signed by the parties concerned．此协议将由各有关方面签署。
Authorities concerned have forbidden such a practice.
有关部门对这种做法亮了红灯。
They called on all departments concerned to take prompt steps to promote the development of light industry．他们要求各有关部门迅速采取措施，促进轻工业发展。
None of this is nice for the people concerned, especially those with large student debts.
这些对相关人员来说都不是好事，尤其是那些背负着巨额学生债务的人。
A good relationship involves concern and sensitivity for each other's feelings.
一段美满的恋情需要彼此关心并体恤对方的情感。