A.電荷 B.電流 C.電壓 D.電阻
A.20~30mPa·s B.20~40mPa·s C.10~15mPa·s D.15~30mPa·s
A.膨潤(rùn)土 B.有機(jī)土 C.抗鹽土 D.劣質(zhì)土