Basically, a firewall is a (145) process or a set of integrated processes that runs on a router or (146) to control the flow of networked application traffic (147) through it. Typically, firewalls are placed on the entry point to a (148) network such as the Internet. They could be considered traffic cops. The firewall’s (149) is to ensure that all communication between an organization’s network and the Internet conform to the organization’s policies.

A．pass

B．passed

C．passing

D．passes

对电厂锅炉而言,热损失最大的一项是机械不完全燃烧损失。