Network managers have long awaited practical voice-over-IP (VOIP)solutions. VOIP promises (71) network management and decreases costs by (72) a company’s telephony and data infrastructures into one network. And a VOIP solution implemented at a company’ s head -quarters with far -reaching branch offices can (73) tremendous amounts of (74) in long distance phone bills, provided that solution delivers POTS -like voice (75) over the Internet.

（71）处填（）。

A．complicated

B．useful

C．ease

D．orderly

何谓设备故障的直接参数？何谓设备故障的间接参数？试述采用间接特征参数进行设备故障诊断的优缺点。