What Cisco IOS feature examines packets received to make sure that the source address and interfaceare in the routing table and matck the interface that the packet was received on？（） ["MPLS Traffic Engineering","Dynamic access-lists","Authentication","Receive ACL","Unicast RPF"]
基因工程药物主要有哪几类？试举例说明。
苏联学前教育理论流派以其鲜明的（）主张为标识，重视学前教育机构的工作是其特色。
Which two statements about the DiffServ model are true？（） ["a class can be identified as a single application， multiple applications with similar service needs，or be based on the source or destination IP address","a drawback of the DiffServ field in the MAC header to mark frames into behavior aggregates （BAs）","DiffServ uses the DiffServ field in the MAC header to mark frames into behavior","the DiffServ field occupies the same eight bits of the MAC header that were previously used for the ToS field","the first six high-order bits of the DiffServ field are used to identify the Resource Reservation Protocol （RSVP） value","the primary goal of DiffServ is scalability"]
简述设定游戏角色在游戏中的应用。
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