Question

    Many electronic parts are made of hard materials that break easily. That makes them tough to use in products that need to bend. Now, Sam Yoon and his team have developed a thin mesh (网状物) that can both bend and conduct electricity.

His team started out with something called acrylonitrile, a clear liquid often used to make thin plastic fibers. Yoon and his team mixed this material with another liquid, which acted as a solvent. A solvent is something that can make other substances into liquids. Then, they squeezed the mix through a very tiny pipe: As the mixture was sprayed through the air, the solvent evaporated(挥发)and the acrylonitrile molecules linked up to make long chains, creating a type of plastic known as PAN. The researchers continually squeezed the mixture through the pipe. A single long PAN fiber was created. The scientists moved the pipe back and forth as the PAN was squeezed out. It ended up creating a layer that looked something like a spider’s web.

PAN, like most plastics, doesn’t conduct electricity. So the team’s next step would normally be to add a coating of metal so that electricity could flow through it. But it could be tough sticking such coatings on PAN. So the researchers added an extra step. They sprayed a thin coating of an inert metal onto the PAN. Inert metals, like gold, typically don’t react with other materials. The researchers then added another layer of PAN fiber at the top of the first, web-like layer. They provide temporary support, helping the metal-sprayed base resist sinking during the next step.

The researchers connected the fiber-covered frame to a negatively changed electrode. Then they dipped the fiber-covered frame into a solution that included the liquid copper. The team turned on the electric current for about one minute to make it run through the solution. The copper in the solution was attached to all of the fibers. But it stuck only to those that wore a metal jacket. Besides adding a thin layer of copper that conducts electricity, this process helped bond the PAN strands together at places, where they touched each other, Yoon notes.

The researchers then attached all of the fibers to a thin, clear layer of plastic, which had sticky backing, like a Band-Aid. Finally, the team dipped all of these into a liquid that made any of the PAN fibers that lacked a copper jacket into liquids. Only those that can be used to conduct electricity were left. Because the fibers were very thin and widely separated, light waves easily travel through the mesh. The copper coating acted just like a wire, permitting electricity to flow freely across it.

1.The team used another liquid in the process to  .

A.make acrylonitrile evaporate B.turn acrylonitrile into plastic fibers

C.make acrylonitrile conduct electricity D.conduct electricity instead of acrylonitrile

2.What should the team do first when using PAN?

A.Make it easy to break. B.Make it react with other materials.

C.Make it conduct electricity. D.Find a way to make it into a liquid.

3.What does the underlined word those in the last paragraph refer to?

A.The thin plastics. B.Just the copper coatings.

C.All the PAN fibers. D.All the copper-coated fibers.

Answer

1.B

2.C

3.D

【解析】

这是一篇说明文。文章主要介绍了一种既可以弯曲又可以导电的PAN塑料纤维的制作过程。

1.细节理解题。根据第二段的Then, they squeezed the mix through a very tiny pipe: As the mixture was sprayed through the air, the solvent evaporated(挥发)and the acrylonitrile molecules linked up to make long chains, creating a type of plastic known as PAN. The researchers continually squeezed the mixture through the pipe. A single long PAN fiber was created. (然后，他们挤压混合物让他们通过一个小管，随着混合物在空中喷洒，溶剂挥发了，丙烯腈分子连接起来成为一条长链，创建成一种名为PAN的塑料。研究人员不断地挤压混合物通过小管，一个纯的PAN纤维就做好了)可知，Yoon他们把丙烯腈和另一种液体混合，是为了让丙烯腈成为塑料纤维。B. turn acrylonitrile into plastic fibers(把丙烯腈转化成塑料纤维)符合以上说法，故选B项。

2.细节理解题。根据第三段的PAN, like most plastics, doesn’t conduct electricity. So the team’s next step would normally be to add a coating of metal so that electricity could flow through it.(PAN，像大多数的塑料，是不能导电的。因此，团队的下一步通常是添加一层金属，这样电流就可以通过了)可知，要使用PAN的第一步是让它可以导电。C. Make it conduct electricity.(让它可以导电)符合以上说法，故选C项。

3.词义猜测题。根据最后一段的Finally, the team dipped all of these into a liquid that made any of the PAN fibers that lacked a copper jacket into liquids. Only those that can be used to conduct electricity were left.可知，最后，团队将所有这些浸入一种液体中，这种液体可以使任何缺少铜外壳的PAN纤维变成液体。只有那些可以导电的被剩下来了。结合上下文可知，those那些具有铜外套的PAN纤维。D. All the copper-coated fibers.(所有有铜外套的纤维)符合以上说法，故选D项。