在OSI参考模型中，物理层的任务是透明地传送比特流。下列选项中，对这里的“透明”解释正确的是(17)。

(75) Virus Security Software is designed to detect, eliminate or quarantine computer viruses before they are able to harm a computer or server networked system.

(75)

Computer hardware engineers research, design, develop, and test computer hardware and supervise its manufacture and(73). Hardware refers to computer(74), circuit boards, computer systems, and related equipment such as keyboards, modems, and printers.

(73)

(71)

The major goal of USB was to define an external expansion bus which makes adding(71) to a PC as easy as hooking up a telephone to a wall-jack. USB 2.0 is an evolution of the USB 1.1(72), providing a higher performance interface.

(70)

(68)

计算机网络中，物理地址是指(37)，在IP地址和物理地址之间建立映射是因为(38)，实现IP地址与物理地址之间映射的协议是(39)。

若FTP地址写为ftp：//123：213@222.18.8.241，则该地址中“123”的含义是FTP服务器的(59)，若FTP地址为ftp：//222．18．8．241，则该地址对应连接的FTP服务器用户名字为(60)。