传统的驱动电源有单电源驱动电路和双电源驱动电路，新型电源有高压电压斩波电源。
参考答案：错
It’s said that there are plenty of hotels in Shanghai. There _____ be any difficulty for you to find somewhere to stay.
A．wouldn’t
B．shouldn’t
C．mustn’t
D．needn’t
人体感染病毒后最先出现的抗体是（）
A.IgG
B.IgA
C.IgD
D.IgM
E.IgE
