The model test and the exploration example show that this method can be used to explore ground water in volcanic area.

模型算例和勘探实例表明这一方法可以用于勘探火山岩地区地下水。

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So Douglass especially promoted, championed his interracial friendship as a kind of test case, on-the-ground example of how democracy could work, and in his hope, an inspiration for others in the United States.

NPR: Lincoln and Douglass Shared Uncommon Bond