A.鋼軌阻抗 B.鋼軌阻抗和道床電阻 C.鋼軌阻抗和送電端電壓 D.鋼軌阻抗、道床電阻和送電端電壓
A.10mm B.20mm C.30mm D.40mm
A.0.5Q B.1Q C.2Q D.2.5Q