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(來回運(yùn)動(dòng)) atoms(原子) between two molten metal droplets(小滴) in a carbon nanotube(納米管)。 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(動(dòng)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(百萬分之一瓦) -- it is quite impressive(給人印象深刻的) in relation to(與。。。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， 運(yùn)行的) micromotor(微型發(fā)動(dòng)機(jī))， 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(納米傳送帶)， which moves tiny particles along like cars in a factory.
6. Nanotechnology(納米技術(shù)) 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(預(yù)想) a day when nanomachines(納米機(jī)器)， powered by nanomotors(納米發(fā)動(dòng)機(jī))， travel inside your body to find disease and repair damaged cells.
練習(xí)：
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(表面張力)。
DPrevious inventions of nanoscale(納米級(jí)的) products.
EThe working principle of the nanomotor.
FPossible fields of application in the future.
指定的四個(gè)段落都沒有明顯的段落主題句(2007年理工類A/B級(jí)概括大意題中四個(gè)指定段落都沒有明顯段落主題句)，考生可以通過通讀指定段落的大意來歸納出段落主題，或借助一些有效的答題技巧確認(rèn)段落主題。以確認(rèn)段落第4段的段落主題為例分析答題技巧：
AAn introduction of a Toyota’s 225 horsepower V6 engine.
BA description of the nanomotor in terms of power and size.
CSurface tension(表面張力)。
DPrevious inventions of nanoscale(納米級(jí)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( 百萬分之一瓦) -- it is quite impressive( 給人印象深刻的) in relation to(與。。。相比 )the tiny scale of the motor. The whole setup is less than 200 nanometers( 納米) on a side， or hundreds of times smaller than the width(寬度) 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(強(qiáng)大的) than a Toyota Camry’s 225 horsepower(馬力) V6 engine.
2.B.解析：段落中沒有明顯的段落主題句，但是段落中出現(xiàn)了大量反映典型細(xì)節(jié)信息的詞語：20 microwatts(微瓦)， 200 nanometers(納米)， hundreds of times smaller than the width of a human hair， 100 million times more powerful， 225 horsepower(馬力)， 這些細(xì)節(jié)信息貫穿全段，從性質(zhì)上它們分別用于描述功率和尺寸大小， 因此可直接判斷B(描述了納米發(fā)動(dòng)機(jī)的功率和尺寸大小)是答案。
提示：如果段落中有明顯的“細(xì)節(jié)信息詞”， 可以考慮利用這些細(xì)節(jié)信息所反映的主題內(nèi)容來確認(rèn)段落主題。