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.
They called on all departments concemed to take prompt steps to promote the development of light industry.
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.
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.
We are all concerned about the pollution of the environment here.
Parents are naturally conerned for their children's safety.
下面是concerning的例句：
This is a proposal concerning the construction of the new airport.
Yesterday we wrote him a letter concerning the business arrangement.
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.
请注意，下列语句的区别：
They were concerned(worried)about the matter.
They were concerned(implicated)in the matter.
They were concemed (connected)with the matter.
此外，作为特定词组，as far as I am concerned解作in my opinion;as far as sth is concerned解作concerning sth/ talking about sth。例：
As far as I'm concerned，this plan is impractical.
As far as funding is concerned，some banks have agreed to provide loans.
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