某商场商品数据库的商品关系模式P(商品代码,商品名称,供应商,联系方式,库存量),函数依赖集F={商品代码→商品名称,(商品代码,供应商)→库存量,供应商→联系方式}。商品关系模式P达到______;该关系模式分解成______后,具有无损连接的特性,并能够保持函数依赖。 希赛公司欲对其内部的信息系统进行集成,需要实现在系统之间快速传递可定制格式的数据包,并且当有新的数据包到达时,接收系统会自动得到通知。另外还要求支持数据重传,以确保传输的成功。针对这些集成需求,应该采用______的集成方式。
A. 远程过程调用
B. 共享数据库
C. 文件传输
D. 消息传递
Obtaining Drinking Water from Air Humidity Not a plant to be seen, the desert ground is too dry. But the air contains water, and research scientists have found a 1 of obtaining drinking water from air humidity. The system is based completely on renewable energy and is therefore autonomous. Cracks permeate the dried-out desert ground and the landscape bears testimony to the lack of water. But even here, where there are no lakes, rivers or groundwater, considerable quantities of water are stored in the air. In the Negev desert in Israel, for example, annual average relative air humidity is 64 percent-in every cubic meter of air there are 11.5 milliliters of water. German research scientists have found a way of converting this air humidity autonomously into drinkable water. "The process we have developed is based exclusively on renewable energy sources 2 thermal solar collectors and photovoltaic ceils, 3 makes this method completely energy-autonomous. It will 4 function in regions where there is no electrical infrastructure." says Siegfried Egner, head of the research team. The principle of the 5 is as follows: hygroscopic brine-saline solution which absorbs moistureruns down a tower-shaped unit and absorbs water from the air. It is then sucked 6 a tank a few meters off the ground in which a vacuum prevails. Energy from solar collectors 7 up the brine, which his diluted by the water it has 8 . Because of the vacuum, the boiling point of the liquid is lower than it would be under 9 atmospheric pressure. This effect is known from the mountains: as the atmospheric pressure there is lower than in the valley, water boils at temperatures distinctly below 100℃. The evaporated, non-saline water is condensed and runs down through a completely filled tube in a controlled manner. The gravity of this water column 10 produces the vacuum and so a vacuum pump is not needed. The reconcentrated brine 11 down the tower surface again to absorb moisture from the air. "The concept is suitable for various water 12 . Single-person units and plants supplying water to entire hotels are conceivable, " says Egner. Prototypes have been built for 13 system components-air moisture absorption and vacuum evaporation-and the research scientists have already 14 their interplay on a laboratory scale. In a further 15 the researchers intend to develop a demonstration facility.
A. repaired
B. cancelled
C. tested
D. copied
Mt. Desert Island The coast of the State of Maine is one of the most irregular in the world. A straight line running from the southernmost coastal city to the northernmost coastal city would measure about 225 miles. If you followed the coastline between these points, you would travel more than ten times as far. This irregularity is the result of what is called a drowned coastline. 1 At that time, the whole area that is now Maine was part of a mountain range that towered above the sea. As the glacier (冰川) descended, however, it expended enormous force on those mountains, and they sank into the sea. As the mountain sank, ocean water charged over the lowest parts of the remaining land, forming a series of twisting inlets and lagoons (咸水湖) . The highest parts of the former mountain range, nearest the shore, remained as islands. 2 Marine fossils found here were 225 feet above sea level, indicating the level of the shoreline prior to the glacier. The 2, 500-mile-long rocky coastline of Maine keeps watch over nearly two thousand islands. Many of these islands are tiny and uninhabited, but many are home to thriving communities. Mt. Desert Island is one of the largest, most beautiful of the Maine coast islands. Measuring 16 miles by 12 miles, Mt. Desert was essentially formed as two distinct islands. 3 For years, Mt. Desert Island, particularly its major settlement, Bar Harbor, afforded summer homes for the wealthy. Recently though, Bar Harbor has become a rapidly growing arts community as well. But, the best part of the island is the unspoiled forest land known as Acadia National Park. Because the island sits on the boundary line between the temperate (温带) and sub-Arctic zones, the island supports the plants and animals of both zones as well as beach, inland, and alpine (高山的) plants. 4 The establishment of Acadia National Park in 1916 means that this natural reserve will be perpetually available to all people, not just the wealthy. Visitors to Acadia may receive nature instruction from the park naturalists as well as enjoy camping, cycling, and boating. Or they may choose to spend time at the archeological museum, learning about the Stone Age inhabitants of the island. The best view on Mt. Desert Island is from the top of Cadillac Mountain. 5 From the summit, you can gaze back toward the mainland or out over the Atlantic Ocean and contemplate the beauty created by a retreating glacier. A. It also lies in a major bird migration lane and is a resting spot for many birds. B. Mt. Desert Island is one of the most famous of all of the islands left behind by the glacier. C. The wealthy residents of Mt. Desert Island selfishly keep it to themselves. D. The term comes from the activity of the ice age. E. This mountain rises 1, 532 feet, making it the highest mountain on the Atlantic seashore. F. It is split almost in half by Sones Sond, a deep and narrow stretch of water seven miles long.