单项选择题

下列复用方式中，(112)是光纤通信中使用的复用方式，EI载波把32个信道按(113)方式复用在一条2.048Mb/s的高速信道上，每条话音信道的数据速率是(114)。

A．时分多路
B．空分多路
C．波分多路
D．频分多路
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单项选择题
(接上一题)该点与计划S曲线的水平距离表示(70)。
A.进度超前的时间
B．进度拖后的时间
C．超额完成的任务量
D．拖欠的任务量
单项选择题
Personal firewall is a technology that helps(66)intruders from accessing data on your PC via the Internet or another network, by keeping(67)data from entering or exiting your system.Hackers do not just target national security organizations for(68): They want your tax returns, network passwords, or bank account numbers. And you do not want the FBI kicking in your door because someone hijacked your PC to(69)in the latest denial-of-service attack on the Internet. Now that 'always-on' broadband connections such as cable modems and digital subscriber line are becoming more popular, home users are at risk. Fortunately, you can protect your data. Firewalls can block(70)attacks and protect your PC from outside threats.
A．allow
B．prevent
C．invite
D．get
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