A socket is basically an end point of a communication link between two applications. Sockets that extend over a network connect two or more applications running oncomputers attached to the network. A sockettwo addresses:. Sockets provide acommunication channel between one or more systems.
There aresockets separately using TCP and UDP.

A．unique

B．separate

C．same

D．dependent

二氧化碳储罐的工作压力是（）千帕。