[外语类试卷]大学英语六级模拟试卷270及答案与解析.doc
《[外语类试卷]大学英语六级模拟试卷270及答案与解析.doc》由会员分享,可在线阅读,更多相关《[外语类试卷]大学英语六级模拟试卷270及答案与解析.doc(32页珍藏版)》请在麦多课文档分享上搜索。
1、大学英语六级模拟试卷 270及答案与解析 一、 Part I Writing (30 minutes) 1 Directions: For this part, you are allowed 30 minutes to write a composition on the title: Should Class Attendance Be Optional? You should write at least 150 words following the outline given below in Chinese. 1. 描述现在大学课堂及讲座上常见的现象:态度不认真,睡觉,发短信及出勤
2、率低 因此提出大学课堂是否应该采取自愿而非强制。 2列举原因。 3我的看法。 Should Class Attendance Be Optional 二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-4, mark
3、: Y (for YES) if the statement agrees with the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 The Wonderful World of Small Theres a quiet revolution going on, and its
4、 name is nanotechnology. A host of innovations are coming our way. Some seem almost magical, like the new material created in 2004 by Ray Baughman, a professor at the University of Texas. Its stronger than steel, transparent, very, very light. A hectare-size sheet would weigh just 280 grams. When th
5、e professor announced that he hadnt decided what to call it, he started to get emails from around the world suggesting names. Since it was so light and strong, people started calling it “mithril“-the name of a highly prized type of armor used in The Lord of Rings. There are other discoveries too-per
6、haps not so astounding, but practical and pleasant. Now there are socks that dont get smelly, pants that resist stains, windows that repel dirt and toilets that clean themselves. All this results from exploring the world of the very, very small. Nano comes from the Greek word from dwarf. Usually nan
7、otechnology is defined as the study and manipulation of matter smaller than 100 nanometers(毫微米 )-thats the scale of things like molecules and viruses. Ten hydrogen atoms pressed together against each other are just one nanometer long. And one million nanometers fit into a millimeter. Hard to grasp?
8、Think of it this way: If everyone in Manila were a nanometer wide, the entire population, standing shoulder to shoulder, would fit on your thumbnail. Stunning Uses of Nanotechnology Like Alice in Wonderland, researchers in Nanoland find themselves in a world where old rules dont apply. Small things
9、behave differently. This is behind several innovations, including the self-cleaning toilet. The toilet bowl is sealed with a super-smooth glaze (涂层 ) that has microscopic holes under 30 nanometers. Because theyre smaller than bacteria or other tiny particles, theres not enough room for dirt to get s
10、tuck in the surface. Flushing is basically all the work you have to do. Researchers in Nanoland are also making really, really small things with astonishing properties-like the carbon nanotube. Chris Papadopoulos of the University of Victoria, says, “The carbon nanotube is the poster boy for nanotec
11、hnology.“ In your pencil, carbon, in the form of graphite (石墨 ), is soft and easily broken. But a carbon nanotube is tough as nails-much tougher in fact. Its very thin sheet graphite thats formed into a tube. These tiny straw-like cylinders, which can be as small as half a nanometer wide, are up to
12、100 times stronger than steel and six times lighter. They are the hardest, stiffest, strongest materials known and are among the worlds best conductors of heat and electricity. They can carry some 1000 times more electricity current than copper wire. Everybody wants them, but until now theyve been i
13、n short supply and pricey. The current annual production, worldwide, is only 300 kilograms. At $ 860 a gram, carbon nanotubes cost 50 times more than gold. When it comes to finding uses for carbon nanotubes, the range is huge. The National Research Council Canada (NRC) is looking at harnessing their
14、 strength by embedding them in construction materials, among other applications. The Boeing Company thinks nanotubes may be the source of futute improvements for high-performance aircraft. Some of the most stunning uses come out of Ray Baughmans research. Employing what he calls the “ancient technol
15、ogy of spinning,“ Baughman and his team developed a way of spinning carbon nanotubes into fibers that are four times tougher than spider silk, the toughest natural filament (细丝 ). Since they also conduct electricity, the futuristic yarns could be woven into “smart“ clothing that stores electricity,
16、is potentially bulletproof and incorporates sensors capable of adjusting the temperature of garment. The fibers could also be made into cables for suspension bridges much longer than any we have now. And then there are Baughmans superstrong, superlight sheets. Papadopoulos explains that one of the r
17、easons scientists are excited by the sheets is that they would make ideal solar sails. He says, “With a solar sail, you are allowing the pressure of the suns light to propel you through space the same way wind powers a sailboat.“ But there is also something in this for the earthbound traveler. Using
18、 an ordinary microwave oven, Baughmans team was able to weld one of his sheets between two pieces of plexiglass (树脂玻璃 ). Afterwards, it still conducted electricity and remained transparent. One idea, therefore, is to put these sheets in windshields of the car and run current through them to defrost
19、car windows. Medicine and Nanotechnology Many disease-causing bacteria and viruses are nano size. So only nanotechnology would offer us ways of fighting back. Nucryst Pharmaceuticals has come up with a winning formula that combines nanoscience with old-fashioned folk wisdom. The ancient Greeks used
20、silver to promote healing and prevent infection, but the treatment took a back seat when antibiotics came on the scene. Nucryst has revived and improved on the old cure by coating a burn-and-wound bandage with nano-size silver particles that are more reactive than the bulk form of metal. They penetr
21、ate into the skin and work steadily. As a result, burn victims can have their dressings changed as little as once a week. Before Nucryst, such dressings had to be changed several times a day, a painful procedure that involved removing a healing cream. In 2004, Nucryst produced over three million ban
22、dages, and its sales topped $ 30 million. 7O% of chronic-wound patients who were not healing at the expected rate got better with the use of these bandages. Copy Nature with Nanotechnology With new instruments that reveal natural structures down to the last atom, nanotechnologists ability to copy na
23、ture has taken off. When Bharat Bhushan, a mechanical engineering professor at Ohio State University, wanted to make a super-smooth surface, he decided to copy lotus leaves. Scientists have long known that the leaves shed water very well: Theyre waxy and covered with tiny nano-size bumps, so water r
24、olls off. Bhushan succeeded in making a polymer (聚合体 ) sheet that was equally smooth. “If you applied it to glass, you could have windows that dont need washing.“ says Bhushan. Hicham Fenniri, a chemistry professor at the Univeristy of Alberta, took a similar tack to make artificial joints act more
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
下载文档到电脑,查找使用更方便
2000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 外语类 试卷 大学 英语六级 模拟 270 答案 解析 DOC
