科学家们为海洋生物开发了一种新的分类系统。

Scientists have developed a new ___classification system for marine organisms.

调查数据使用了基于收入水平的分类进行分析。

The survey data was analyzed using a ___classification based on income levels.

在政府机构中，按安全级别对文件进行分类至关重要。

The ___classification of documents by security level is crucial in government agencies.