单项选择题
A.(-∞,+∞)B.(-∞,0)C.(0,+∞)D.[0,1]
A.2.17,1.65B.-2.17,-1.65C.-2.17,1.65D.2.17,-1.65
A.液面B.垫脚C.沉淀物D.漂浮物