考前必看:2021年考研英语工学类阅读理解模拟题及答案(三十三)
发布时间:2020-10-12
英语是考研初试当中比较拉分的科目,历来令不少考生又爱又恨。许多考生的英语都有很大的进步空间,因此英语该如何学就成为了众多考生关心的重点。想要学好英语,实战经验很重要。下面,51题库考试学习网为大家带来考研初试英语科目的一些模拟试题,正在备考的小伙伴赶紧练起来吧。
Bryant Linares has one heck of a secret family
recipe: how to make
world-class diamonds. Seven years ago his father, Robert, produced a diamond in a high-pressure chamber of carbon gas and dropped it into
an acid solution to clean it off. When he returned the next morning, he expected to find the usual yellow
stone——a crude artificial
diamond of some use to industry, perhaps, but not the stuff
of dreams. At first there didn\'t seem to be any stone at all. Then he saw, at the bottom of the beaker, so clear it was almost invisible, a perfect quarter-carat crystal of pure
carbon. “It was the eureka
moment,” says Bryant. His
father had managed what many scientists had given up on long ago: to manufacture a stone that wouldn\'t
look out of place on an engagement ring.
Man-made diamonds are nothing new——industry started making them in the
1950s, and each year
about 80 tons of low-quality synthetic diamonds are used in tools like drill
bits and sanders. High-quality crystals, though, open
up huge possibilities, jewelry being the least of them. Scientists are most excited about the prospect
of making diamond microchips. As chips have shrunk over the years, engineers have struggled with ways of
dissipating the heat they create. Because silicon, the main component of semiconductors, breaks down at about 200 degrees Fahrenheit, some experts believe a new material will
be needed in a decade or so. Diamonds might fit the bill. They can withstand 1,000 degrees, and electrons move through them so easily that they would tend not
to heat up in the first place. Engineers could cram a lot more circuits onto a
diamond-based micro-chip——if
they could perfect a way of making pure crystals cheaply.
The race is on. After working in secrecy
for years refining their technique, the Linareses\' company, Apollo Diamond, now
spits out 20 carats a week, both
for jewelry and for diamond wafers that could be fashioned into microchips.
Rivals have also been busy. Gemesis, a Sarasota, Fla., firm, has developed a “diamond
growth chamber”——a press that
squeezes out high-quality diamonds in much the same way that the early presses
made rough ones. Gemesis is making blue diamonds——rare and sought-after gemstones.
Chipmakers are also getting into the act.
The Japanese firm Nippon Telegraph and Telephone has already made prototype
diamond semiconductors, and
the Japanese government is actively promoting the technology. Most U.S.
research is going on in universities and military labs, but Intel has recently taken an
interest. Before the technology is ready for prime time, chipmakers will have to come up with a
way to keep out impurities during manufacturing. And the attribute that makes
diamonds so attractive——their
hardness——also makes them
difficult to manipulate.
The new diamonds are likely to show up
first as tiny light-emitting diodes, or LEDs, in
flat-screen displays and high-definition televisions. And then, of course, there\'s jewelry. Although synthetics still carry a stigma, even experts can\'t tell the difference.
Natural-diamond merchants claim they aren\'t worried, but De Beers has made a device that can
distinguish between the natural stones and the synthetics and is distributing
it to jewelers. Will consumers care? We might find out next year when Gemesis
is ready to market its blue diamonds in the United States.
注(1):本文选自Newsweek,10/25/2004, p60-61, 2p, 3c
注(2):本文习题命题模仿对象2002年真题Text 4
1. From the first paragraph, we learn that______________.
[A] All the diamonds are almost invisible.
[B] Many scientists had tried hard to make
perfect crystals long time ago.
[C] His father expected to find a diamond
used in industry.
[D] Diamond are produced with carbon gas.
2. Which of the following statements is not
true according to the text?
[A] Diamond can withstand higher degree
than silicon.
[B] The main component of semiconductors
will be replaced in a few years.
[C] High-quality crystals have least usages, esp. in jewelry.
[D] Engineers could not find perfect ways
of making pure crystal cheaply.
3. According to the passage, why can the companies increase and
perfect their production
of diamond?
[A] They all work in secrecy.
[B] They have improved their techniques.
[C] They have developed their own diamond
chambers.
[D] They have turned the rough diamond to
high-quality one‘s.
4. Which of the following best defines the
word “attribute”(Line 5, Paragraph 4)?
[A] quality
[B] contribution
[C] appearance
[D] value
5. The new diamond is Not first used
in___________.
[A] LEDs
[B] flat-screen display
[C] high-definition televisions
[D] prototype diamond semiconductor
答案:B C B A D
以上就是51题库考试学习网为大家带来的全部内容,希望能给大家一些帮助。51题库考试学习网提醒:在最后阶段,调整自己的心态也是非常重要的,每年都有考生临考前放弃,所以小伙伴们要注意不要给自己太大的压力哦。另外,小伙伴们如果还有其他关于考研信息的疑问,也可以留言咨询哦。
下面小编为大家准备了 研究生入学 的相关考题,供大家学习参考。
A.实脉
B.沉弦脉
C.细涩脉
D.结代脉
A.肽键 B.氢键 C.离子键 D. 二硫键
B.不同的内容有着相似的发展轨迹
C.每一种内容的发展都是获得与衰退的复杂结合
D.衰老可以通过干预来适当延缓
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