英语语法分析

Stratigraphy is used for dating portable art.

地层学被用于测定可移动艺术品的年代。

The study of stratigraphy is playing in the form of units.

地层学的研究是以地层单位的物质形式运作的。

From the view of stratigraphy, they all belong to the Cretaceous period.

从地层学上看，它们都属于白垩纪。