单项选择题
A.ZPW•ZXJ B.ZPW•PJZ C.ZPW•JZ D.ZPW•PJC
A.ZPW•S B.ZPW•SH C.ZPW•SHP D.ZPW•SHH
A.≥25MΩ B.≥50MΩ C.≥100MΩ D.≥500MΩ