单项选择题
A.岩层; B.土层; C.不透水层; D.透水层
A.0.65m; B.0.8m; C.0.35m; D.0.5m
A.急流槽 B.截水沟 C.排水沟 D.盲沟
A.0.5m; B.2m; C.1m; D.0.1m
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