2013年全国职称英语考试理工类押题试卷(4)

　　第3部分：概括大意与完成句子（第23～30题，每题1分，共8分）

　　下面的短文后有2项测试任务：(1)第23～26题要求从所给的6个选项中为第1～4段每段选择1个最佳标题；(2)第27～30题要求从所给的6个选项中为每个句子确定1个最佳选项。

The Tiniest Electric Motor in the World

　　Scientists recently made public the tiniest electric motor ever built. You could stuff hundreds of them into the period at the end of this sentence. One day a similar engine might power a tiny mechanical doctor that would travel through your body to remove your disease.

　　The motor works by shuffling atoms between two molten metal droplets in a carbon nanotube. One droplet is even smaller than the other. When a small electric current is applied to the droplets, atoms slowly get out of the larger droplet and join the smaller one. The small droplet grows－but never gets as big as the other droplet－and eventually bumps into the large droplet. As they touch, the large droplet rapidly sops up the atoms it had previously lost. This quick shift in energy produces a power stroke.

　　The technique exploits the fact that surface tension－the tendency of atoms or molecules to resist separating－becomes more important at small scales. Surface tension is the same thing that allows some insects to walk on water.

　　Although the amount of energy produced is small－20 microwatts－it is quite impressive in relation to the tiny scale of the motor. The whole setup is less than 200 nanometers on a side, or hundreds of times smaller than the width of a human hair. If it could be scaled up to the size of an automobile engine, it would be too million times more powerful than a Toyota Camry’s 225 horsepower V6 engine.

　　In 1988, Professor Richard Muller and colleagues made the first operating micromotor, which was 100 microns across, or about the thickness of a human hair. In 2003, Zettl’s group created the first nanoscale motor. In 2006, they built a nanoconveyor, which moves tiny particles along like cars in a factory.

　　Nanotechnology engineers try to mimic nature, building things atom-by-atom. Among other things, nanomotors could be used in optical circuits to redirect light, a process called optical switching. Futurists envision a day when nanomachines, powered by nanomotors, travel inside your body to find disease and repair damaged cells.

　　23. Paragraph 2 _____

　　24. Paragraph 4 _____

　　25. Paragraph 5 _____

　　26. Paragraph 6 _____

　　A. An Introduction of a Toyota’s 225 Horsepower V6 Engine

　　B. A Description of the Nanomotor in Terms of Power and Size

　　C. Surface Tension

　　D. Previous Inventions of Nanoscale Products

　　E. The Working Principle of the Nanomotor

　　F. Possible Fields of Application in the Future

　　27. Doctors envision that the nanomotor would travel through human bodies to _____.

　　28. Surface tension means the tendency of atoms or molecules to_____.

　　29. Nanoconveyors could be used to_____.

　　30. Applying a small electric current causes atoms to _____.

　　A. remove disease

　　B. resist separating

　　C. shuffle between two molten metal droplets

　　D. power nanornachines

　　E. sop up molecules from the large droplet

　　F. transport nanoscale objects