活性硅酸钙带式过滤机的工作原理是什么？
燃气用热熔式衬塑铝合金管外层为6063高抗腐蚀铝合金管材；内层为PE100高密度聚（）塑料管材。 ["丙烷","丙烯","乙烯","甲烯"]
Diesel engine injection lag is caused by（） ["compressibility of the fuel","high fuel oil supply flow","scored plunger and barrel packing","excessive air turbulence"]
与销售包装不同的是运输包装（）。 ["重装潢","重装饰","重防护","重流通"]
衬塑铝合金管综合工程造价合理，和传统的钢管相比，大大（）了后续维护费用和设备材料投资。 ["节省","浪费","中和","延长"]
说出帧中继支持的主要业务？
