什么是食物网？
推进“互联网+”行动重大意义是（） ["增加网民数量","使国民有更好的上网体验","顺应世界经济科技发展的必然要求"]
影响教学媒体选择的因素有哪些？
What will an Easy VPN hardware client require in order to insert its protected network address when it connects using network extension mode？（） [" RADIUS or LDAP"," an internal router running EIGRP"," Reverse Route Injection and OSPF or RIPv2"," the VPN appliance to be deployed in line with the firewall"]
装配式整体结构中的不承受内力的结构和拼缝可采用混凝土浇筑，其强度等级不应低于（）。 ["C15","C20","C25","C30"]
说明生物多样性的直接使用价值？
