变压器出厂前进行的参数和性能的试验称为（）试验。 ["出厂","预防性","检修","安装"]
美的（）是指美所具有的物质化形态的特性。
Which of these technologies is characterized as being a multipoint Layer 2 VPN that connects two or more customer devices using Ethernet bridging techniques?（） ["DPT","MPLS","VPLS","CWDM"," DWDM"," SONET\/SDH"]
我国教育技术发展取得哪些经验？
我国专利权的客体包括（） ["发明","实用新型","外观设计","科学发现"]
艺术是在特定的（）中由艺术家创造出来的、为观众所体验的具有表现性的符号系统。
