去年也有学者对甘肃省的土地利用变化情况进行了研究，本文选择不同的角度对这一主题进行整体研究。
Last year, some scholars studied land use change in Gansu province. But a different perspective on this theme is selected in this paper to conduct a comprehensive study.
本文就是在前人研究的基础上，利用了3s技术，从空间角度分析了城市扩展导致下垫面变化，从而引起地下水补给量的减少。
This paper is based on the investigation of the fore people, makes use of 3s technologies, analyzes the bottom mat changed from the city expansion, which causes the fall of groundwater level.
利用绘图分析的方法分析金属切削刀具工作角度的变化规律。
The graphic method of analyzing the changing law of working angles for the wetting tools ispreseted.
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