单项选择题
A.-0.5s/d~0.5s/dB.-1.0s/d~1.0s/dC.-1.5s/d~1.5s/dD.-2.0s/d~2.0s/d
A.1.55VB.3.0VC.3.7VD.5.0V
A.AC电源B.恒定交流C.直流可调D.交流可调