基站内主要的直流供电设备有（）和（）等。
参考答案：整流器；蓄电池组
(d) State, giving reasons, whether you agree with the vendor’s agent that the client, who is purchasing the business, will obtain a credit for the VAT element of the purchase price. (3 marks)
某多孔材料的孔隙率为30%，则其密实度为( )
A．30% B．60%C．70% D．100%
