ARPANET is the predecessor of Internet，and it is a（）
A. circuit switching network
B. message switching network
C. packet switching network
D. hybrid switching network
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In OSI/RM architecture,the lowest is（）
A. application layer
B. network layer
C. transmission layer
D. physical layer
In OSI/RM architecture, the first layer that provide end-to-end service from buttom to top is（）
A. network layer
B. transmission layer
C. data link layer
D. application layer
In OSI/RM architecture,the function of physical layer is（）
A. data link access control and management
B. Transparently transmitting bitstreams
C. transmitting data frames between physical entities
D. transmitting and receiving data message
What is UNICEF designed to do（）
A. Provide emergency food and healthcare to children suffering the destruction of war
B. Provide money to help poor people in the world
C. Promote the cooperation in education among countries
D. Provide food to areas stricken by catastrophes
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