带权为9，2，4，6的4个叶子结点构造一棵哈夫曼树，该树的带权路径长度为______。

File infectors are also called______viruses．

AWeb site is often more effective as a(n)______tool than a selling tool．

To access information on the Intemet，a user must first log on to the client computer'S______network．

The complete database application can be divided into three major categories：data presentation．businesslogic，and data______．

In the system development process，______and pseudo code are tools used by programmers in theimplementation phase．

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(72)

在PowerPoint的各种视图中，显示单个幻灯片以进行文本编辑的视图是普通视图；可以对幻灯片进行移动、删除、添加、复制、设置动画效果，但不能编辑幻灯片中具体内容的视图是(2)；PowerPoint可以为文本、图形等对象设置动画效果，设置动画效果可以从(3)主菜单进行；在PowerPoint的字体设置中，不能进行(4)。

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(70)

电子邮件中的两个协议中，(66)协议是接收邮件的协议，(68)协议是发送邮件的协议。

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