概括大意Scientists
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：
1.Paragraph 2
2.Paragraph 4
3.Paragraph 5
4.Paragraph 6
AAn introduction of a Toyota’s 225 horsepower V6 engine.
BA description of the nanomotor in terms of power and size.
CSurface tension(表面张力)。
DPrevious inventions of nanoscale(纳米级的) products.
EThe working principle of the nanomotor.
FPossible fields of application in the future.
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：
AAn introduction of a Toyota’s 225 horsepower V6 engine.
BA description of the nanomotor in terms of power and size.
CSurface tension(表面张力)。
DPrevious inventions of nanoscale(纳米级的) products.
EThe working principle of the nanomotor.
FPossible fields of application in the future.
2.Paragraph 4 ____。
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。
提示：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。