(难度B/A级/2008年理工类教材新增文章)

　　1.    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.

　　2. The motor works by shuffling（来回运动） atoms（原子） between two molten metal droplets（小滴） in a carbon nanotube（纳米管）. 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 （吸入）the atoms it had previously lost. This quick shift in energy produces a power stroke（动力行程）. 

　　3.     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.

　　4.    Although the amount of energy produced is small -- 20 microwatts（百万分之一瓦） -- it is quite impressive（给人印象深刻的） in relation to（与...相比） 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 100 million times more powerful than a Toyota Camry’s 225 horsepower V6 engine.

　　5.    In 1988, Professor Richard Muller and colleagues made the first operating（工作的， 运行的） micromotor（微型发动机）, which was 100 microns（微米） 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（纳米传送带）, which moves tiny particles along like cars in a factory.

　　6.     Nanotechnology（纳米技术） 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（预想） a day when nanomachines（纳米机器）, powered by nanomotors（纳米发动机）, travel inside your body to find disease and repair damaged cells. 

　　练习：

 

 

　　指定的四个段落都没有明显的段落主题句（2007年理工类A/B级概括大意题中四个指定段落都没有明显段落主题句），考生可以通过通读指定段落的大意来归纳出段落主题， 或借助一些有效的答题技巧确认段落主题。以确认段落第4段的段落主题为例分析答题技巧：

　　4.    Although the amount of energy(能量)  produced is small -- 20 microwatts( 百万分之一瓦)  -- it is quite impressive( 给人印象深刻的) in relation to（与...相比 ）the tiny scale of the motor. The whole setup is less than 200 nanometers( 纳米) on a side, or hundreds of times smaller than the width(宽度) of a human hair. If it could be scaled up to the size of an automobile engine, it would be 100 million times more powerful（强大的） than a Toyota Camry’s 225 horsepower（马力） V6 engine.

　　2．B．解析：段落中没有明显的段落主题句， 但是段落中出现了大量反映典型细节信息的词语：20 microwatts(微瓦), 200 nanometers（纳米）, hundreds of times smaller than the width of a human hair， 100 million times more powerful, 225 horsepower（马力）, 这些细节信息贯穿全段， 从性质上它们分别用于描述功率和尺寸大小， 因此可直接判断B（描述了纳米发动机的功率和尺寸大小）是答案。

　　如果段落中有明显的“细节信息词”， 可以考虑利用这些细节信息所反映的主题内容来确认段落主题。

　　从2007年考题的出题情况和2008年教材的编写情况来看，2008年职称英语考试仍然将可能从教材中摘选一部分试题直接作为考题。2008年考题难度应该与2007年考题难度相当。