Methods: Using cluster sampling, the water fluoride content, depth of well, materials of well as well as quality of blocking soil of FCRWQIP before 1996 in Xinyang were measured.
方法 :采取整群抽样办法 ,对被调查县 1996年前的所有改水工程水氟含量、打井深度、井壁结构材料和井周封闭土质进行调查分析。
