A.0.5≤η B.η≤0.8 C.η>1 D.0.5≤η≤0.8
A.3 B.1 C.2 D.4
A.4個晶閘管 B.4個二極管 C.2個晶閘管和2個二極管 D.2個晶閘管和2全個場效應(yīng)管