concerned，concerning
这两个词的词义并不相同，用法亦有异。
Concerned是分词形容词，其意为“有关的”（involved）；concerning是由分词转换而成的介词，其意为“关于”（relating to）。请看下面的例句：
This agreement will be signed by the parties concemed.
此协议将由各有关方面签署。
They called on all departments concemed 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。
由例句可见，concerned用作形容词解作“有关的”时，是后置定语，大都放在它所修饰的名词之后。但在verb“to be”之后而同样解作“关于”时，则要用be concerned with的形式，如：
This book is concerned with English usage.
此书是与英语惯用法有关。
值得注意的是，concerned（亦可表示动词之意）也可解作“关心”、“担心”解，与之搭配的介词为at、about或，用作此意时，concerned也是形容词。例：
He was deeply concerned at the news.
听到这个消息时，他深为担忧。
We are all concerned about the pollution of the environment here.
对这里的环境爱到污染，我们都感到不安。
Parents are naturally conerned for their children's safety.
父母自然关心他们儿女的安全。
下面是concerning的例句：
This is a proposal concerning the construction of the new airport.
这是关于兴建新机场的一项建议。
Yesterday we wrote him a letter concerning the business arrangement.
昨天我们就业务安排问题写了一封信给他。
在个别场合下，concerned with可以和concerning互换使用，原因是从句which are concerned with中的which are 省略了。例如：
We had several disputes concerning/（which are）concerned with this matter.
关于此事，我们曾争论过数次。
请注意，下列语句的区别：
They were concerned（worried）about the matter.
他们为此事而担忧。
They were concerned（implicated）in the matter.
他们参与此事。
They were concemed （connected）with the matter.
他们与此事有关。
