界自然的生物体和物体被分类的三大主要分界(动物、植物和矿物)之一 One of the three main divisions(animal, vegetable, and mineral) into which natural organisms and objects are classified.
用来分类的符号。 A symbol that classifies.
图书馆的书是按照[根据]科目分类的。 The books in the library are classified by/according to subject.
图书馆的书是按科目分类的。 The books in the library are classified by subject.