They are generally classified into three broad categories—stones, stony irons and irons.

它们通常被分为三大类——石头、陨铁石和铁。

These methods can be classified into three types of informational writing: factual, descriptive and process.

这些方法可分为三类信息写作：事实性、描述性和过程性。

Patients are classified into three categories.

病人被归为三种类型。

Storage can be broadly classified into two types.

存储设备大致分为两类。

Errors are classified into the following groups.

错误可以分类为以下几组。