关于流行性感冒的流行病学特征，下列哪项是错误的（） ["流感患者及隐性感染者为主要传染源","动物亦可能为主要的贮存宿主和中间宿主","呼吸道经空气飞沫传播","乙型流感均为散发"]
总体数据库设计时，文件设计的基本内容主要包括几个方面？
Your MPLS implementation is currently using internal backdoor links. What can you do to minimize the impact of having these links？（） [" use BGP as the CE-PE routing protocol"," use OSPF as the CE-PE routing protocol"," use EIGRP as the CE-PE routing protocol"," use the SP to redistribute routes as external routes for OSPF and EIGRP"," use route redistribution at each location to ensure external routes are imported into the IGP"]
明知校舍或教育教学设施有危险，而不采取措施，或不及时报告，致使发生重大人员伤亡事故的，对直接责任人员，处三年以上有期徒刑或者拘役；后果特别严重的处三年以上七年以下有期徒刑。
以下关于阳台施工技术准备说法正确的是（）。 ["A.所有的预制阳台安装施工前应编制专项施工方案 ","B.预制阳台专项施工方案需经施工总承包企业项目负责人和总监理工程师批准 ","C.预制阳台安装施工前应对施工人员进行技术交底，并由交底人和被交底人双方签字确认 ","D.预制阳台安装施工前，应编制合理可行的施工计划 ","E.预制阳台施工前应明确预制阳台吊装的时间节点"]
生物多样性的三个层次指（）、物种多样性和生态系统多样性。
