样品预处理是为了()。
A.去除样品中的杂质;
B.富集待测物;
C.提高分析仪器的灵敏度;
D.排除样品中的干扰;
E.消除样品中待测物与基体的反应。
参考答案:A, B, D
He used to in a small village , but he has been used to in a big city .
A.live, living . B. live, live. C. living , living.
1Cr18Ni9Ti奥氏体不锈钢中含铬为()%
A.40
B.18
C.25
D.30