采用可变长子网掩码技术可以把大的网络分成小的子网，例如把子网掩码为255.255.0.0的网络69.16.0.0分为两个子网，假设第一个子网为69.16.0.0/17，则第二个子网为(38)。假设用户Xl有4000台主机，则至少应给他分配(39)个C类网络。

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In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

The purpose of the testing phase of software development is not to(71)the absence of errors in the programs being tested, but rather to find as many errors as possible. This statement may seem to contradict one's intuitive notion of a successful test of a piece of(72); however, a successful test is one in which errors have been found, net one in which no errors have been detected.

 There are generally two kinds of testing method: human testing and machine testing. In most companies where systems are developed, the first testing that occurs is not machine testing, but rather the detection of errors through(73), team efforts, referred to as walkthroughs and inspection. With these methods, the author of the program forms a group with others who represent programming expertise or who may be part of the project team.

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For each blank, choose the best answer from the four choices and write down on the answer sheet.

It is claimed that Al applications have moved from laboratories to the real world. However, conventional von Neumann computers are(66)for Al applications, because they are de- signed mainly for numerical processing. In a larger yon Neumann computer, there is a larger ratio of memory to processing power and consequently it is even less efficient. This(67)remains no matter how fast we make the processor because the length of the computation becomes dominated by the time required to move data between(68)and memory. This is called the yon Neumann(69). The bigger we build the machines, the worse it gets. The way to solve the problem is to diverse from the traditional architectures and to design special ones for Al applications. In the research of future Al architectures, we can take advantages of many(70)or currently emerging concepts. in computer architecture, such as dataflow computation, stack machines, tagging, pipelining, systolic array, multiprocessing, distributed processing, database machines, and inference machines.