题目内容

Since the popularity of smart phones, people spend lots of time on their phones, either messaging other people,

______news, or playing games.___________I think cell phones have made life more_________, I don’t think spending a lot of time on cell phones is a good idea.

Firstly, spending too much time on cell phones may__________cancer. Scientific studies have__________that low levels of radiation(辐射) are given off from the batteries(电池) of cell phones. Not only that, but phones are constantly using microwaves to send and _________information. Since many people use their cell phones near their heads, long time exposure(暴露) could eventually lead to some very___________and unhealthy effects.

Secondly, when people spend too much time on their cell phones, they__________on the things going on around them. This has been proven over and over again by___________who use their phones while in their cars. This has been such a major cause of car___________, because drivers are too distracted(分心) by their phones to__________the road, that most states in the U.S. have banned(禁止) the __________of cell phones while driving. There are also other cases showing how using cell phones can_________people to miss out on the things around them. For example, I went hiking with a friend a few weeks ago. She was so__________to her cell phones the whole time that she missed out on all the__________things we saw on the mountains, and didn’t get a___________to experience the same awe(敬畏) of nature as I was able to experience.

Lastly, spending too much time on cell phones makes people forget how to have normal conversations._______, when people use text messaging, they use a form of shorthand known as “Netspeak” to________on the size of messages and make typing them on small keyboards fast and easy.________this, many people forget how to spell and use grammar__________.

1.A. reading B. learning C. spreading D. reporting

2.A. Since B. Because C. Unless D. While

3.A. interesting B. meaningful C. convenient D. enjoyable

4.A. add to B. result from C. turn to D. lead to

5.A. raised B. proven C. reviewed D. examined

6.A. seek B. store C. receive D. collect

7.A. powerful B. harmful C. important D. beneficial

8.A. break in B. fall back C. miss out D. catch up

9.A. drivers B. visitors C. passengers D. players

10.A. accidents B. trades C. crimes D. losses

11.A. pull out into B. pay attention to C. get across D. go along

12.A. use B. call C. answer D. message

13.A. command B. force C. allow D. cause

14.A. accounted B. attracted C. attached D. affected

15.A. terrible B. strange C. beautiful D. funny

16.A. moment B. mind C. way D. chance

17.A. Therefore B. Besides C. However D. Instead

18.A. count B. work C. save D. mark

19.A. In case of B. According to C. For fear of D. As a result of

20.A. correctly B. carefully C. regularly D. normally

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25.A.doorB.windowC.curtainsD.sleeves
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28.A.foldedB.raisedC.pressedD.shook
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30.A.raisedB.gaveC.reac hedD.cupped
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38.A.getB.escapeC.passD.survive
39.A.agreementB.doubtC.demandD.surprise
40.A.run intoB.hold backC.get throughD.put off

Hummingbirds (蜂鸟) are one of nature’s most energetic fliers and the only birds to hover in the air by relying on their strength alone.

Now scientists have found that it is the ratio (比值) of the bird’s wing length to its width that makes them so efficient. The discovery is helping experts compete with 42 million years of natural selection to build helicopters that are increasingly efficient.

David Lentink, an assistant professor at Stanford University in California, tested wings from 12 different species of hummingbirds, which he sourced from museums. He placed them on a machine used to test the aerodynamics (气力学) of the helicopter blades (桨叶). Professor Lentink’s team used the same machine to test the blades from an advanced micro-helicopter used by the UK’s army. They found that the micro-helicopter’s blades are as efficient at hovering as the average hummingbirds.

But while the micro-helicopter’s blades kept pace with the average hummingbird wings, they could not keep up with the most efficient hummingbird’s wing. The wings of Anna’s hummingbird were found to be about 27 percent more efficient than the man-made micro- helicopter’s blades.

While Professor Lentink wasn’t surprised at nature’s superiority, he said that helicopter blades have come a long way. “The technology is at the level of an average hummingbird,” he said. “A helicopter is really the most efficient hovering device that we can build. The best hummingbirds are still better, but I think it’s amazing that we’re getting closer. It’s not easy to match their performance, but if we build better wings with better shapes, we might match hummingbirds.”

Professor Lentink said that we don’t know how hummingbirds maintain their flight in a strong wind, how they navigate (确定方向) through branches, or how they change direction so quickly. He thinks that great steps could be made by studying wing aspect ratios—the ratio of wing length to wing width. Understanding these abilities and characteristics could be a benefit for robotics and will be the focus of future experiments.

1.What did the scientists find about hummingbirds?

A. Their wings are long and wide.

B. They can hover in the air for a long time.

C. The ratio of their wing length to wing width is very important.

D. They are the most energetic flier in nature.

2.Which is the right order of Professor Lentink’s research?

① Tested wings from different species of hummingbirds.

② Got resources from museums.

③ Analyzed the results and drew a conclusion.

④ Tested the blades from a micro-helicopter.

A. ①②③④ B. ②①③④ C. ②④①③ D. ②①④③

3.According to Professor Lentink, what will be the focus of future experiments?

A. To know how hummingbirds can fly in a strong wind.

B. To know how hummingbirds change direction so quickly.

C. To develop a new kind of helicopter.

D. To study the secrets of hummingbirds.

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