TCP/IP (71) layer protocols provide services to the application (72) running on a computer. The application layer does not define the application itself, but rather it defines (73) that applications need--like the ability to transfer a file in the case of HTTP. In short, the application layer provides an (74) between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP (75) layer consists of two main protocol options--the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

（74）处填（）。

A．iteration

B．object

C．interface

D．activity

赏古诗答题。

1．诗中_______一词写出了杨柳的枝繁叶茂，_______一词写出了梦境的一再出现。

2．这首诗的后两句抒发了诗人怎样的感情？

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