未知题型 Currently the Pentium chip or(71), made by(72), is the most common CPU though there are many other companies that produce processors for personal computers. One example is the CPU made by Motorola which is used in Apple computers. With faster processors the clock speed becomes more important. Compared to some of the first computers which operated at below 30 megahertz((73))the Pentium chips began at 75 megahertz in the late 1990g. As of mid 2003 speeds now exceed 3000 + megahertz or 3 gigahertz(check your local computer store for the latest speed). It depends on the(74)that the chip is housed in, or the(75), as to whether you are able to upgrade to a faster chip. The motherboard contains the circuitry and connections that allow the various component to communicate with each other.

未知题型 PPP帧的格式如图10-1所示。某PPP帧的数据部分(用十六进制写出)是：7D 5D 7D 5E FE 65 7D 5E。对于该PPP帧，下列说法错误的一项是(44)，该帧的真正数据是(45)。

未知题型 在OSI参考模型中，顶层和最底层分别为(13)，中继器工作在OSI参考模型中的(14)。