TCP/IP （） layer protocols provide services to the application （） running on a computer. The application layer does not define the application itself, but rather it defines （） that applications need — like the ability to transfer a file in the case of HTTP. In short, the application layer provides an （） 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 （） layer consists of two main protocol options — the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

TCP/IP（）layer protocols provide services to the application.

A．application

B．transport

C．link

D．network

阅读下面文言语段，翻译画线的句子

景公问于晏子曰：“为政何患？”晏子对曰：“患善恶之不分。”公曰：“何以察之？”对曰：“审择左右。左右善，则百僚各得其所宜，而善恶分。”

孔子闻之曰：“此言也信矣！善进，则不善无由入矣；不善进，则善无由入矣。”

（1）何以察之？

（2）左右善，则百僚各得其所宜，而善恶分。

（3）此言也信矣！善进，则不善无由入矣。