单项选择题
A.15000标本(45000测试) B.5000标本(15000测试) C.10000标本(30000测试) D.1500标本(4500测试) E.永远无需更换
A.1ul B.2ul C.3ul D.5ul E.10ul
A.0.01ul B.0.1ul C.0.5ul D.1ul E.2ul