A.主極T1為正,T2為負;門級電壓G為正,T2為負B.主極T1為負,T2為正;門級電壓G為正,T2為負C.主極T1為正,T2為負;門級電壓G為負,T2為正D.主極T1為負,T2為正;門級電壓G為負,T2為正
A.I+和III+B.I-和III-C.I+和III-D.I-和III+