Basically, a (71) is a standalone process or a set of integrated processes that runs on a router or server to control the flow of (72) application traffic (73) through it. Typically, firewalls are (74) on the entry point to a public network such as the Internet. They could be considered traffic cops. The firewall’ s (75) is to ensure that all communication between an organization’s network and the Internet conform to the organization’s security policies.

72（）

A．network

B．networked

C．net

D．networky

当部分块状石灰的表层被煅烧成十分致密的釉状物，这类石灰称为（）。

A.熟石灰粉

B.生石灰粉

C.欠火石灰

D.过火石灰