As we know, when administrative main subject take some actions, it legally enjoys free verdictive right in given scope.

行政主体在作出行政行为时，依法享有一定范围内的自由裁量权。

The latter is the main subject.

后者是主要的主题。

Pathology is a main subject of medicine.

病理学是医学专业的主干学科。

Background: Area behind the main subject.

背景：主调后面的范围。

What tis the main subject of this writing?

这个作品的主题是什么?。