局域网中负责差错与流量控制的子层是（）

对于上消化道大出血的老年患者，调整输血量最好根据（）。

A.血压情况

B.中心静脉压

C.尿量

D.心率情况

E.以上均不是

现代农业指（）。

A.欧洲模式

B.美国模式

C.日本模式

D.20世纪40年代以后，经济发达国家的农业

道氏理论的主要观点包括( )。

A．市场价格指数可以解释和反映市场的大部分行为

B．市场的每一级波动可分为上升五浪、下跌三浪

C．交易量在确定趋势中有重要作用

D．收盘价是最重要的价格

关于胃窦炎的描述，错误的是（）。

A.肩胛征

B.胃窦黏膜粗大

C.黏膜皱襞斜行、横行或交叉排列

D.胃窦张力增高

E.充盈像，胃窦轮廓呈细齿状

Current Group, a Germantown-based technology firm, has taken over an ordinary looking house in Bethesda and turned it into a laboratory for smart-grid technology, the system the company believes will bring the nation’s electricity grids into the digital age.

In the front yard stands a utility pole hooked up to a special transformer that connects the power lines to high-speed Internet. Hundreds of sensors attached to the lines monitor how power flows through the home. That information is then sent back to the utility company.

The process lets a utility more efficiently manage the distribution of electricity by allowing two-way communication between consumers and energy suppliers via the broadband network on the power lines. Based on data they receive from hundreds of homes, utilities can monitor usage and adjust output and pricing in response to demand. Consumers can be rewarded with reduced rates by cutting back on consumption during peak periods. And computerized substations can talk to each other so overloaded circuits hand off electricity to those that have not fully loaded, helping to prevent blackouts.

Some utility companies have launched initiatives to give consumers data about their energy consumption habits in an effort to lower energy bills. Smart-grid technology takes such programs further by automating electricity distribution, which would make grids more reliable and efficient.

By partnering with utilities, the company hopes to tap into $4.5 billion in stimulus grants intended to encourage smart-grid development. When he announced the funding, President Obama pointed to a project in Boulder, Colo. , as an example of a successful smart-grid experiment. Current is one of the companies working on the project.

Current’s chief executive Tom Casey believes the technology will help utility companies better distribute electricity produced by renewable resources, such as solar panels or wind farms. " A smart grid’s system can be paired up with the renewable resources so that when the renewable source is varying, the overall load can be varied as well, " Casey told the House Select Committee on Energy Independence and Global Warming. " This will reduce or eliminate the need for backup coal or gas-based power generation plants. \

Why is the system called " smart-grid " technology（）

A. Because with all the sensors and transformers, the equipment looks very modern

B. Because with all the data, they can help the utilities make clever decisions

C. Because the technology is making good use of computer intelligence

D. Because the consumers can have wise ideas on the usage of electricity