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问题 解答题

轮船顺水航行80千米所需要的时间和逆水航行60千米所用的时间相同．已知水流的速度是3千米/时，求轮船在静水中的速度．

答案

设船在静水中的速度是x千米/时．

由题意得：

80
x+3
=
60
x-3
．

解得：x=21．

经检验：x=21是原方程的解．

答：船在静水中的速度是21千米/时．

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单项选择题

WLANs are increasingly popular because they enable cost-effective connections among people, applications and data that were not possible, or not cost-effective, in the past. For example, WLAN-based applications can enable fine-grained management of supply and distribution (51) to improve their efficienty and reduce (52) . WLANs can also enable entirely new business processes. To cite but one example, hospitals are using WLAN-enabled point-of-care applications to reduce errors and improve overall (53) care. WLAN management solutions provide a variety of other benefits that can be substantial but difficult to measure. For example, they can protect corporate data by preventing (54) through rogue access points. They help control salary costs, by allowing IT staffs to manage larger networks without adding staff. And they can improve overall network mananement by integrating with customers’ existing systems, such as OpenView and UniCenter. Fortunately, it isn’t necessary to measure these benefits to justify investing in WLAN management solutions, which can quickly pay for themselves simply by minimizing time-consuming (55) and administrative chores.

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