这份报告将市场细分为多个子类别，以便进行更详细的分析。

The report divides the market into several ___sub-levels for more detailed analysis.

矿工们正在主矿井下方挖掘三个子层以扩大开采范围。

The miners are digging three ___sub-levels below the main shaft to extend the mining area.

这个数学课程在基础级别和高级级别之间设置了四个子级别。

This math course has four ___sub-levels between the basic and advanced levels.