The Tiniest Electric Motor in the World
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 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 stroke2.
3. The technique exploits the fact that surface tension -- the tendency of atoms or molecules to resist separating -- becomes more important at small scales3. 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 -- it is quite impressive in relation to the tiny scale of the motor4. The whole setup5 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 engine6, 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 micromotor, which was 100 microns across7, 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.
6. 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 yur body to find disease and repair damaged cells.
词汇：
shuffle v. 来回运动 nanometer n. 纳米，毫微米
molten adj. 熔化的 micromotor n. 微电机
droplet n. 小滴
nanotube n. 纳米管 nanoconveyor n. 纳米传送带 nanotechnology n. 纳米技术
bump v. 碰撞 mimic v. 模仿
sop v. 吸入
stroke n. 行程，冲程
microwatt n. 微瓦 nanomotor n. 纳米发动机
nanomachine n. 纳米机器
注释：
1. ever：比以往任何时候，曾经。如：
This is the best book I have ever read.
(这是我读过的书中最好的一本。)
2. power stroke：动力行程
3. at small scales：在小等级上。这里指的是 “在纳米等级上”。
4. it is quite impressive in relation to the tiny scale of the motor：与电动机的小等级相比，功率是相当可观了。in relation to 是“与……相比”。如：
The city is quite large in relation to its population.
(就人口而言，这个城市相当的大。)
5.setup：装置。这里指 nanomotor。
6.If it could be scaled up to the size of an automobile engine：如果纳米电动机能按比例放大到汽车发动机的尺寸。scale…up to 是 “把……按比例放大到……”。
7.across：从一端到另一端
练习：
1.Paragraph 2 A An introduction of a Toyota’s 225 horsepower V6 engine.
2.Paragraph 4 B A description of the nanomotor in terms of power and size.
3.Paragraph 5 C Surface tension.
4.Paragraph 6 D Previous inventions of nanoscale products.
E The working principle of the nanomotor.
F Possible fields of application in the future.
5.Doctors envision that the nanomotor would travel through human bodies to __________ .
6.Surface tension means the tendency of atoms or molecules to __________ .
7.Nanoconveyors could be used.to __________ .
8.Applying a small electric current causes atoms to __________ .
A remove disease
B resist separating
C shuffle between two molten metal droplets
D power nanomachines
E sop up molecules from the large droplet
F transport nanoscale objects
答案与题解：
1.分析文章标题：The Tiniest(最小的) Electric(电动的) Motor(发动机) in the World(在世界上)
文章主题词：the tiniest, electric motor
2. 分析被选项小标题：
A An introduction(引入， 介绍) of a Toyota(丰田汽车)’s 225 horsepower (马力)V6 engine(发动机)(motor的近义词).
B A description(描述) of the nanomotor(纳米发动机
) in terms of (在...方面)power(动力， 权力) and size(大小，尺寸).
C Surface tension(表面张力).
D Previous(以前的， 早先的) inventions(发明) of nanoscale(纳米级的) products(产品).
E The working principle (工作原理)of the nanomotor(纳米发动机).
F Possible(可能的) fields(领域， 天地， 运动场) of application(运用) in the future(将来).
分析：A， B， D和E与文章主题相关， 因此成为答案可能性较大， 而C和F初看起来偏离文章主题，因此成为答案的可能较小。
3.解答概括大意题
A. An introduction(引入， 介绍) of a Toyota(丰田汽车)’s 225 horsepower (马力)V6 engine(发动机)(motor的近义词).
B. A description(描述) of the nanomotor(纳米发动机
) in terms of (在...方面)power(动力， 权力) and size(大小，尺寸).
C. Surface tension紧张(状态), 拉紧, 张力(表面张力).
D. Previous(以前的， 早先的) inventions(发明) of nanoscale(纳米级的) products(产品).
E. The working principle (工作原理)of the nanomotor(纳米发动机). F. Possible(可能的) fields(领域， 天地， 运动场) of application(运用) in the future(将来).
1. Paragraph 2 ____.
(第1段)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(相似的) engine(发动机)might power a tiny mechanical doctor that would travel through your body to remove your disease.
(第2段)The motor works by shuffling(来回移动) atoms(原子) between(在...之间) two molten(熔化的) metal(金属) droplets (小滴) in a carbon(碳) 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 the atoms it had previously lost. This quick shift in energy produces a power stroke.
1.E 借助段落主题词droplet关注段首句， 段首句就是该段主题句， 该句内容与E一致。从该段具体内容上看： 该段介绍了纳米发动机的工作原理：两小滴金属熔液通上微弱电流，大的小滴的原子就会缓慢逸出，加入小的小滴，后者体积不断增大，到一定阶段，就会与前者碰撞，这时，大的小滴便夺回它失去的原子，这就是一次 power stroke (动力行程，动力冲程)，此时就会产生发动机的动功。原子如此来来去去运动，就象发动机活塞一样。这就是纳米发动机的工作原理。由此也可以判断出E 是答案。
提示1：如果段落中某个词多次重复出现， 至少重复出现3次以上， 而且是贯穿整个段落出现， 则这个词通常就是其所在段落的主题词; 如果段落中某个词与其近义词， 或家族词汇在段落中出现了至少3处以上， 而且也是贯穿整个段落出现， 则该词及其家族词汇或近义词通常就是其所在段落的主题词。
提示2：段落小标题通常应该直接包括段落主题词或间接涉及段落主题词， 如：段落中出现段落主题词的家族词汇，近义词， 或在意义上与段路主题词呼应。
A. An introduction(引入， 介绍) of a Toyota(丰田汽车)’s 225 horsepower (马力)V6 engine(发动机)(motor的近义词).
B. A description(描述) of the nanomotor(纳米发动机
) in terms of (在...方面)power(动力， 权力) and size(大小，尺寸). C. Surface tension(表面张力).
D. Previous(以前的， 早先的) inventions(发明) of nanoscale(纳米级的) products(产品).
F. Possible(可能的) fields(领域， 天地， 运动场) of application(运用) in the future(将来).
2. paragraph 4 ___.
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(倍/时期/次) smaller than the width(宽度) of a human hair(头发). 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 V6 engine.
2.B motor及engine很可能就是其所在段落的主题词。 由此判断A或B可能是答案。借助段落中的细节信息结构(涉及到数字的结构， 分别描述大小和动力)， 由此判断B是答案。
提示3：
段落中出现的细节信息结构(尤其涉及到数字的信息)也是重要的解题线索。
A. An introduction(引入， 介绍) of a Toyota(丰田汽车)’s 225 horsepower (马力)V6 engine(发动机)(motor的近义词).
C. Surface tension(表面张力).
D. Previous(以前的， 早先的) inventions(发明) of nanoscale(纳米级的) products(产品).
F. Possible(可能的) fields(领域， 天地， 运动场) of application(运用) in the future(将来).
3. paragraph 5 ___.
In 1988, Professor Richard Muller and colleagues made the first operating (工作的， 操作的)micromotor(微型发动机), 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(纳米传送带), which moves tiny particles along like cars in a factory.
3. D 段落中出现了典型细节信息结构， --涉及到数字的时间，从过去的时间到现在的时间，由此判断段落主题与关于历史的叙述相关。 因此D是答案。从段落的具体内容上看， 该段介绍了发明纳米发动机之前的一些纳米等级的机械产品，如体积大一些的纳米发动机，微型发动机，纳米传送带，纳米机器等。选项 D 概括了本段的大意。
A. An introduction(引入， 介绍) of a Toyota(丰田汽车)’s 225 horsepower (马力)V6 engine(发动机)(motor的近义词).
C. Surface tension(表面张力).
F. Possible(可能的) fields(领域， 天地， 运动场) of application(运用) in the future(将来).
4. paragraph 6 ___.
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 (未来主义者)envision(想象) a day when nanomachines, powered(被供以动力) by nanomotors, travel(旅行) inside your body to find disease (疾病)and repair(修复) damaged(受损的) cells(细胞).
4. F Nanomotors是段落主题词，关注多次涉及段落主题词的段尾句内容与F一致。 因此F是答案。 从内容上看：第六段预想了纳米发动机的用途，如用于光电路以改变光的方向 (redirect light) 和驱动纳米机器进入人体，消灭病灶。选项 F “Possible fields of application in the future” 概括了本段的大意。
A. remove(去除， 移动) disease(疾病)
B. resist separating
C. shuffle between two molten metal droplets
D. power nanomachine
E. sop up molecules from the large droplet
F. transport nanoscale objects
被选项语法结构特征一致， 都是动词短语结构。
5.Doctors(医生) envision(幻想) that the nanomotor(纳米发动机) would travel through(穿越) human bodies to __________ .
5.答案是 A。题干出现 doctors envision，选项的内容应与医学有关，选项 A 是 remove disease, 正好与题干的内容相配，是答案。也可利用问题句中的细节信息词doctor作为答案线索， 在文章中查找答案相关句：
(第一段)One day a similar(相似的) engine(发动机) might power(给...提供动力) a tiny(微小的) mechanical(机械的) doctor that would travel through your body to remove your disease.
B. resist(反抗) separating(分开)
C. shuffle between two molten metal droplets
D. power nanomachine
E. sop up molecules from the large droplet
F. transport nanoscale objects
6.Surface tension (表面张力)means(意味着) the tendency(倾向/趋势) of atoms(原子) or molecules (分子)to __________
6. B 利用问题句中的细节信息词(surface tension)作为答案线索, 在第三段第一句找到答案相关句： “surface tension -- the tendency of atoms or molecules to resist(抗拒， 反抗) separating(分开)-- becomes more important(重要的) at small scales(级别)”。
C. shuffle between two molten metal droplets
D. power nanomachine
E. sop up molecules from the large droplet
F. transport(运输) nanoscale(纳米等级的) objects(物品， 东西)
7.Nanoconveyors(纳米传送带) could be used to(被用于) __________ .
7.F 题干的 nanoconveyor 提示我们，纳米传送带的功能自然是传送纳米等级的物体，所以F 是答案。也可以利用问题句中的细节信息词(nanoconveyors)作为答案线索,找到答案相关句：In 2006, they built a nanoconveyor, which moves(移动) tiny(微小的) particles(粒子) along( 往前) like(象) cars in a factory(工厂). F是定语从句的概括句。
C. shuffle(来回移动) between two molten metal droplets
D. power nanomachine
E. sop up(吸收) molecules from the large droplet
8.Applying(应用， 申请， 施加) a small electric current (电流)causes(造成) atoms(原子) to __________ .
8.C 利用题干的细节信息结构a small electric current作为答案线索， 在文章中找到答案相关句。
When a small electric current is applied to (被施加到)the droplets(小滴), atoms(原子) slowly get out of (从...出来)the larger(更大的) droplet and join(加入) the smaller one. The small droplet grows(增大) – but never gets as big as (与...一样大)the other droplet – and eventually(最终) bumps into (撞击)the large droplet. As they touch(接触), the large droplet rapidly(迅速地) sops up(吸收) the atoms(原子) it had previously(以前) lost(失去). This quick shift in (变化) energy(能量) //produces(产生) a power stroke(动力形成). E是对该段内容的概括。