题目内容：
回答题：The Tiniest Electric Motor in the WorId
1．Scientists recently made puhlic the tinjest electric motor ever huilt．You could stuff hundrefls of them into the period at the end of this sentence．One day a similar engine might power a tiny mechanical doetor that would travel through your hodv t0 remove your disease．
2．The motor workshy shuffling atoms between two molten metal droplets in a carhon nanotube．One droplet is even smallerthan the other．When a small electric current is applied to the droplets，atoms s1owly get out of the larger droplet and join the smaller one．The sinall droplet grows—hut never gets as big as the other droplet—and eventually humps into the large droplet．As they touch，the large dmplet rapidly sops up the atoms it had prevviously lost．This quick shift in energy produces a power stroke．
3．The technique exploits the flact that surface tension—the tendeney of atoms or molecules to resist separating—becomes more important at small scales．Surfaee tension is the same thing that aUOWS 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 seale of the motor． The whole setup is less than 200 nanometers on a side．Or hundreds of times smaIler than the width of a human hair．If it could he sealed up to the size of an automobile engine，it wonld be 1 00 million times more powerful than a Toyota Camry’s 225 horsepower V6 engine．
5．In 1988，Pmfessor Richard Muller and coeagues made the first operating micromotor，which as 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 panicles along Iike carsin 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．
Paragraph 2_______.
参考答案：
答案解析：