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2015年英语四级考试每日一练(2月9日)

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在线测试本批《每日一练》试题,可查看答案及解析,并保留做题记录 >> 在线做题
  • 第1页:练习试题
单项选择题
1、根据以下资料,回答题:
Directions:In this section,you are going to read a passage with ten statements attached to it.Each statement contains information given in one of the paragraphs.Identify the paragraph from which the information is derived.You may choose a paragraph more than once.Each paragraph is marked with a letter.Answer the questions by marking the corresponding letter on Answer Sheet 2.
Here’s the Totally Amazing Wonder Material That Could Revolutionize Technology
A.In the technology industry,every new product or service seems to come with the promise that it is an innovation with the potential to change the world.Graphene(石墨烯),a form of carbon,might actually do just that.
B.“Graphene is a wonderful material,”Jeanie Lau,a professor of physics at the University of California at Riverside,told Fortune.“It conducts heat 10 times better than copper and electricity 100 times better than silicon,is transparent like plastic,extremely lightweight,extremely strong,yet flexible and elastic.In the past decade,it has taken the scientific and technology communities by storm,and has become the most promising electronic material to supplement or replace silicon.”
C.Graphene has already found its way into a number of compelling applications,Lau said.For instance,“since it is both transparent and electrically conductive—two attributes rarely found in the same material in nature—it has tremendous potential as the transparent electrode in monitors.displays;solar cells,and touch screens,”she explained.“Companies such as Samsung that invest heavily in this area have already secured patents,produced prototypes,and are expected to bring products to market in a few years.”Wearable electronic devices,aviation components,broadband photodetectors(光电检测器),radiation-resistant coatings,sensors,and energy storage are among numerous other areas of active research.Lau said.
D.For many researchers and investors,the ultimate application is graphene-based transistors,the building blocks of modem electronics.But getting there may take some time.
A child of graphite
E.First produced in a lab back in 2004,graphene is essentially a single layer of pure carbon atoms bonded together in a honeycomb lattice so thin it’s actually considered two-dimensional.“We generally regard anything less than 10 layers of graphene as graphene;otherwise,it’s graphite,”said Aravind Vijayaraghavan,a lecturer in nanomaterials at the University of Manchester.
F.Even“graphene”is a bit of an umbrella term.“To oversimplify,there are two major types of graphene,”Michael Patterson,CEO of Graphene Frontiers,said.The first:“Nanoplatelets,”which are powders or flakes made from graphite.These have been around for a while and are“not really super-sexy,”Patterson said.“You mix them into polymers(聚合物)or inks or rubbers to make them conductive.”In flake form,graphene is already on its way to becoming a commodity,Patterson added.The other type—in sheet or film form—is where graphene’s biggest promise lies.Graphene sheets have“incredible potential for electronics,”Patterson said.In the near term,that potential may manifest in situations where the quantity requirements are“not that great”and where quality or conductivity doesn’t have to be as high,such as in basic touch-screen applications,he said.Products that use graphene in this way could arrive to market in the next six to 1 2 months.
G.Looking a little further out,graphene can be employed in membranes used for water desalination.Lockheed-Martin already has a patented product known as Perforene.“It’s real and it works,but it won’t be economically viable until the product reaches an industrial scale where the cost is measured in pennies per square inch”rather than dollars or tens of dollars per square inch,Patterson explained.
“That’s where we’re working today.”
‘It’s expensive and low-capacity’
H.But use of graphene in semiconductors—the technology’s Holy Grail—is likely a decade away.“Many of the challenges presented by graphene are common to most new materials,”Paul Smith,a patent associate with the Intellectual Property Law Group at Fenwick & West,told Fortune.“The trick is figuring out how to synthesize graphene in a way that first is manufacturable beyond lab scale;second,preserves the desirable properties of the material;and third,can be integrated into a product or technology.”
D.Synthesizing graphene in sheet form is considerably more expensive and time-consuming than producing graphene flakes.Whereas the latter typically involves a“quick and dirty”process by which bulk graphite is disassembled into millions of tiny pieces,Lau explained,large sheets of graphene are carefully“grown”on substrates(基板)such as copper,germanium,or silicon carbide.
J.Graphene sheets are also prone to defects and“very difficult to make in good quality,”Ron Mertens,owner and editor of Graphene-Info.tom,said.Production capacity is also very limited.“There are thousands of small companies that can make graphene,but it’s expensive and low-capacity,”Mertens said.alround wafer measuring one inch in diameter,for instance,costs about$1 00,he added.
K.An even thornier obstacle on the way to graphene transistors is the fact that the material has no“band gap,”an essential property that allows transistors to be turned on and off without leaking electronic charge in the“off”state,said Elias Towe,a professor of electrical and computer engineering at Carnegie Mellon University.
L.“Band-gap engineering has been and remains the biggest challenge in the development of graphene transistors and computer chips.”Lau said.It requires controlling the material almost down at the atomic level,and“that’s really pushing the edges of existing technology,”Patterson said.“In 10 years,we’11 start to see these problems solved.”
‘It is largely a matter of time’
M.If graphene is to succeed as a replacement for silicon,every unit of cost and performance will make a difference,Towe said.
N.“Silicon is hard to displace,with all the billions dollars of investments made in manufacturing infrastructure,”he said.“A replacement for silicon has to offer extraordinary performance at extremely rock-bottom cost to compel industry to change its way.”
O.Though graphene is just 10 years old—in contrast,use of silicon in transistors dates to the early 1950s—considerable progress has already been made.For example,the largest graphene sheet was produced by hand in a laboratory eight years ago;its width was less than that of a human hair.“Nowadays,roll-to-roll printing of graphene sheets up to 1 00 meters long has been achieved,”Lau said.“With the increasing interest,investment,and research in graphene-based technology,I think it is largely a matter of time before the economy of scale kicks in and truly low-cost,large-scale production ofhigh-quality graphene is accomplished,”she added.
注意:此部分试题请在答题卡2上作答。

Nanoplatelet is the powder-or flake-type of graphene that has been used for some time to make conductors and that is being launched on the market.


简答题
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3、题目一
Directions:For this part,you are allowed 30 minutes to write a short essay on thefollowing question.You should  write at least 120 words but no more than 180 words.
Suppose a foreign friend of yours is coming to visit your hometown,what is the most interesting place you would like to take him/her to see and why?
题目二
Directions:For this part,you are allowed 30 minutes to write a short essay on thefollowing question.You should write at least.120.words but no more than.180.words.Suppose a foreign friend of yours is coming to visit China,what is the most interesting place you would like to take him/her to see and why?
题目三
Directions:For this part,you are allowed 30 minutes to write a short essay on thefollowing question.You should write at least.120.words but no more than.180.words.Suppose a foreign friend of yours is coming to visit your campus,what is the most interesting place you would like to take him/her to see and why?



4、“抱抱团”(Free HuggerS)是一项公益行为艺术活动,源于国外。它通过在街头宣传,与主动上前的陌生人拥抱的形式,向社会传递“拒绝冷漠”、“互相关爱”的主题。  “抱抱团”的行为受到了众人的关注,也引起了许多的争议。有人认为,街头拥抱拉近了陌生人之间的感情;也有人认为,仅靠这种活动消除不了陌生人之间的冷漠,况且中国人比较含蓄,采取这样的形式有作秀之嫌(pub |i.c j ty stunt)。


5、北京市交通发达。交通工具多样化。公交车是普通老百姓出门的主要交通工具。每辆大型公共汽车的前、后门各有一位售票员招呼乘客,票价一律1元起价。空调公共汽车的票价为2元至11元。学生票可以打四折(60%d i scount)。北京的出租车也很发达,出租车随处可见,非常方便。在机场、火车站和旅游地,都有出租车昼夜服务。北京地铁是新中国条地铁,三十多年来,累计运送乘客近60亿人次。


6、纳米技术(nanotechnoIogy)是近年来出现的一门高新技术。将纳米技术生产的纳米材料加入到普通的金属、塑料中,会呈现许多普通材料无法比拟的特性。纳米是一种度量单位,一纳米等于百万分之一毫米。纳米技术使人们认识、改造微观世界的水平提到了一个新的高度。世界许多国家的科学家不约而同地断言:纳米技术将推进人类科学技术步入一个新的时代——纳米科技时代(the era of nanotechno| ogy)。


7、在全球变暖的大背景下,低碳经济(| ow-carbon economy)受到越来越多国家的关注。低碳经济是以减少温室气体排放为目标,以低能耗、低污染为基础的经济发展方式。近些年来,科学界以及各国政府已基本达成一致,推行低碳经济是避免气候发生灾难性变化、保持人类可持续发展的有效方法之一。以公众的消费选择引导和鼓励企业开发低碳产品技术,向低碳生产模式转变,终达到减少全球温室气体的效果。


8、You shouM write a short essay entitled Free Admission to Museums?
写作导航
1.引出话题:博物馆对公众免费开放的利与弊;
2.具体阐述博物馆对公众免费开放的好处以及带来的一些问题;
3.提出自已的想法。


9、You shouM write an announcement to welcome students tojoin a club.
写作导航
1.本社团活动的内容;
2.参加本社团的好处;
3.如何加入本社团


10、 You should write a short essay on the topic on a Harmonious Dormitory Life.
写作导航
1.指出宿舍生活未必和谐;
2.简要阐述和谐的宿舍生活带来的好处;
3.从生活方式、处理矛盾等方面阐述如何创造和保持和谐的宿舍生活,
4.进行总结。


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