单项选择题
A.ZPW•S B.ZPW•SH C.ZPW•SHP D.ZPW•SHH
A.≥25MΩ B.≥50MΩ C.≥100MΩ D.≥500MΩ
A.12m B.13m C.不小于14.5m、不大于14.65m D.18m