□54÷6，要使商是三位数，□里最小要填（ ）；要使商是两位数，□里最大要填（

招标投标活动中，每个潜在投标人都享有参与平等竞争的机会和权利，不得设置任何条件歧视排斥或偏袒保护潜在投标人。这体现的是( )原则。

A．公开
B．公平
C．公正
D．诚实信用

五个数1，2，3，4，a的平均数是3，则a=____，这五个数的标准差是_________.

A Battery’s Worst Nightmare(噩梦)

Portable electronics that can be carried about easily are only as good as their batteries and, let’s face it, batteries aren’t very good, especially when compared with, say, petrol, which packs 100 times a battery’s energy into an equal space. That’s why a large group of mechanical engineers (centered at the Massachusetts Institute of Technology, but with partners at other universities and companies) are hard at work in an effort to replace batteries with a tiny engine that runs on fuel. Imagine a battery-free life!When the fuel runs out in your laptop or mobile phone, you just fill up and go.

The engine, about the size of a ten-cent coin, starts with a combustion chamber (燃烧室) that burns hydrogen (氢). Its tiny parts are etched onto silicon wafers (硅片) in the same manner that computer parts are imprinted onto integrated circuits (集成电路). The first engine is made up of five wafers. And since these wafers could be produced in much the same way as computer chips, they could probably be produced quite cheaply.

But the devil in all this nice detail is efficiency(效率). Tiny engine parts don’t always behave like their scaled-up parts of the first engine. Something between the parts can slow down the work, according to Columbia University professor Luc Frechette, one of the engine’s designers. Extreme heat from the combustion chamber is also a problem, often leaking to other parts of the engine.

The scientists’ goal is to create an engine that will operate 10 times better than batteries do. Frechette says that a complete system, with all parts in place and working, will be set up in the next couple of years, but commercial models aren’t available until at least the end of the next ten years. 

小题1:.

. According to the passage, the title suggests that ________.

A．batteries should be greatly improved

B．petrol will be used instead of batteries

C．the time of batteries will be gone forever

D．pollution caused by batteries must be prevented小题2:.

What’s the meaning of the underlined word “devil” (In Paragraph 3)?

A．Problem.　

B．Advantage.　

C．Invention.　

D．Technique.小题3:.

What can we infer from the passage?

A．The new invention doesn’t need any fuel.

B．The new engine has been produced in quantity.

C．The new invention is much cheaper than the battery.

D．The new engine needs to be improved before it’s on sale.小题4:.

. What is the main purpose of this passage?

A．To introduce a new invention to readers.

B．To persuade readers not to use batteries.

C．To show us how the new invention works.

D．To declare when the engine will be on sale.

[说明] 网络拓扑结构如图7-78所示。

[问题2] 在DNS系统中反向查询(reverse query)的功能是______。为了实现网络A中WWW服务器的反向查询，在图7-81和图7-82中进行配置，其中网络ID应填写为______，主机名应填写为______。

搬家前的准备工作是将设备保养干净。（）