只有在指忧虑，担心，关切时，是不可数名词；为抽象名词。

表示使人感兴趣的事物时，是可数名词，复数为concerns。

扩展资料

1、The new legislation concerns health and safety at work.

这项新法规涉及工作场所的健康与安全。

2、I find it difficult to be objective where he's concerned.

只要涉及他，我就难以做到保持客观。

3、Our main concern is to provide quality customer service.

我们最关心的是为顾客提供优质服务。

4、These, then, are the main areas of concern.

总之，这些是人们主要关注的方面。

5、The new regulations will be of benefit to everyone concerned.

新规章将使所有有关人员受益。