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英语六级考试真题 六级考试真题

来源:慢速英语   时间:2020-05-19 15:35:18



  Section A

  Directions:In this section,there is a passage with ten blanks.You are required to select one word for each blank from a list of choices given in a word bank following the passage.Read the passage through carefully before making your choices.Each choice in the bank is identified by a letter.Please mark the corresponding letter for each item on Answer Sheet 2 with a single line through the centre.You may not use any of the words in the bank more than once.

  Steel is valued for its reliability,but not when it gets cold.Most forms of steel __26__ become brittle(脆的)at temperatures below about-25℃unless they are mixed with other metals.Now,though,a novel type of steel has been developed that resists __27__ at much lower temperatures,while retaining its strength and toughness—without the need for expensive __28__.

  Steel's fragility at low temperatures first became a major concern during the Second World War.After German U-boats torpedoed(用鱼雷攻击)numerous British ships,a 2,700-strong fleet of cheap-and-cheerful"Liberty ships"was introduced to replace the lost vessels,providing a lifeline for the __29__ British.But the steel shells of hundreds of the ships __30__ in the icy north Atlantic,and 12 broke in half and sank.

  Brittleness remains a problem when building steel structures in cold conditions,such as oil rigs in the Arctic.So scientists have __31__ to find a solution by mixing it with expensive metals such as nickel.


  Yuuji Kimura and colleagues in Japan tried a more physical __32__.Rather than adding other metals,they developed a complex mechanical process involving repeated heating and very severe mechanical deformation,known as tempforming.

  The resulting steel appears to achieve a combination of strength and toughness that is __33__ to that of modem steels that are very rich in alloy content and,therefore,very expensive.

  Kimura's team intends to use its tempformed steel to make ultra-high strength parts,such as bolts.They hope to reduce both the number of __34__ needed in a construction job and their weight—by replacing solid supports with __35__ tubes,for example.This could reduce the amount of steel needed to make everything from automobiles to buildings and bridges.
















  Section B

  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.

  The future of personal satellite technology is here—are we ready for it?

  A)Satellites used to be the exclusive playthings of rich governments and wealthy corporations.But increasingly,as space becomes more democratized,they are coming within reach of ordinary people.Just like drones(无人机)before them,miniature satellites are beginning to fundamentally transform our conceptions of who gets to do what up above our heads.

  B)As a recent report from the National Academy of Sciences highlights,these satellites hold tremendous potential for making satellite-based science more accessible than ever before.However,as the cost of getting your own satellite in orbit drops sharply,the risks of irresponsible use grow.The question here is no longer"Can we?"but"Should we?"What are the potential downsides of having a slice of space densely populated by equipment built by people not traditionally labeled as"professionals"?And what would the responsible and beneficial development and use of this technology actually look like?Some of the answers may come from a nonprofit organization that has been building and launching amateur satellites for nearly 50 years.

  C)Having your personal satellite launched into orbit might sound like an idea straight out of science fiction.But over the past few decades a unique class of satellites has been created that fits the bill:CubeSats.The"Cube"here simply refers to the satellite's shape.The most common CubeSat is a 10cm cube,so small that a single CubeSat could easily be mistaken for a paperweight on your desk.These mini-satellites can fit in a launch vehicle's formerly"wasted space."Multiples can be deployed in combination for more complex missions than could be achieved by one CubeSat alone.

  D)Within their compact bodies these minute satellites are able to house sensors and communications receivers/transmitters that enable operators to study Earth from space,as well as space around Earth.They're primarily designed for Low Earth Orbit(LEO)—an easily accessible region of space from around 200 to 800 miles above Earth,where human-tended missions like the Hubble Space Telescope and the International Space Station(ISS)hang out.But they can attain more distant orbits;NASA plans for most of its future Earth-escaping payloads(to the moon and Mars especially)to carry CubeSats.

  E)Because they're so small and light,it costs much less to get a CubSat into Earth's orbit than a traditional communications or GPS satellite.For instance,a research group here at Arizona State University recently claimed their developmental small CubeSats could cost as little as$3,000 to put in orbit.This decrease in cost allows researchers,hobbyists and even elementary school groups to put simple instruments into LEO or even having them deployed from the ISS.

  F)The first CubeSat was created in the early 2000s,as a way of enabling Stanford graduate students to design,build,test and operate a spacecraft with similar capabilities to the USSR's Sputnik(前苏联的人造卫星).Since then,NASA,the National Reconnaissance Office and even Boeing have all launched and operated CubeSats.There are more than 130 currently in operation.The NASA Educational Launch of Nano Satellite program,which offers free launches for educational groups and science missions,is now open to U.S.nonprofit corporations as well.Clearly,satellites are not just for rocket scientists anymore.

  G)The National Academy of Sciences report emphasizes CubeSats'importance in scientific discovery and the training of future space scientists and engineers.Yet it also acknowledges that widespread deployment of LEO CubeSats isn't risk-free.The greatest concern the authors raise is space debris—pieces of"junk"that orbit the earth,with the potential to cause serious damage if they collide with operational units,including the ISS.

  H)Currently,there aren't many CubeSats and they're tracked closely.Yet as LEO opens up to more amateur satellites,they may pose an increasing threat.As the report authors point out,even near-misses might lead to the"creation of a burdensome regulatory framework and affect the future disposition of science CubeSats."

  I)CubeSat researchers suggest that now's the time to ponder unexpected and unintended possible consequences of more people than ever having access to their own small slice of space.In an era when you can simply buy a CubeSat kit off the shelf,how can we trust the satellites over our heads were developed with good intentions by people who knew what they were doing?Some"expert amateurs"in the satellite game could provide some inspiration for how to proceed responsibly.