Which three statements about bidirectional PIM are true？（） ["Traffic for a bidirectional group flows along the one shared tree and simultaneously utilizes multiple paths in a redundant network topology","It does not require any traffic signaling in the protocol","Membership to a bidirectional group is signaled using explicit Join messages","It maintains source-specific forwarding state","It reduces memory， bandwidth， and CPU requirement"]
TDM电路仿真技术分为（） ["非结构化仿真模式（SAToP）","结构化仿真模式（CESoPSN）","SDH"]
唐、明、清四朝封建经济迅速恢复和发展的共同原因是什么？其经济发展又各有何特点？这几个朝代政策的调整有什么作用？为什么最终又导致土地兼并严重的恶果？
国标规定，全脂乳粉脂肪不低于（） ["20－25％","26%","30－35％"]
What is an important consideration that should be taken into account when configuring shaped round robin？（） ["It enables policing.","Strict priority is not supported.","WRED must be previously enabled.","It enables WRR"]
排气消声器的功用是什么？
