Watching Microcurrents Flow

　　We can now watch electricity as it flows through even the tiniest circuits. By scanning the magnetic field generated as electric currents flow through objects, physicists have managed ____1____. The technology will allow manufacturers to scan microchips for faults, as well as revealing microscopic defects in anything from aircraft to banknotes.

　　Gang Xiao and Ben Schrag at Brown University in Providence, Rhode Island, visualize the current by measuring subtle changes in the magnetic field of an object and ____2____.

　　Their sensor is adapted1 from an existing piece of technology that is used to measure large magnetic fields in computer hard drives.2”We redesigned the magnetic sensor to make it capable of measuring very weak changes in magnetic fields,” says Xiao.

　　The resulting device is capable of detecting a current as weak as 10 microamperes, even when the wire is buried deep within a chip, and it shows up features as small as 40 nanometers across.

　　At present, engineers looking for defects in a chip have to peel off the layers and examine the circuits visually; this is one of the obstacles ____3____. But the new magnetic microscope is sensitive enough to look inside chips and reveal faults such as short circuits , nicks in the wires or electro migration — where a dense area of current picks up surrounding atoms and moves them along. “It is like watching a river flow,” explains Xiao.

　　As well as scanning tiny circuits, the microscope can be used to reveal the internal structure of any object capable of conducting electricity.3 Fpr example, it could look directly at microscopic cracks in an aeroplane’s fuselage, ____4____. The technique cannot yet pick up electrical activity in the human brain because the current there is too small, but Xiao doesn’t rule it out4 in the future. “I can never say never,” he says.

　　Although the researchers have only just made the technical details of the microscope public, it is already on sale,5 from electronics company Micro Magnetics in Fall River, Massachusetts. It is currently the size of a refrigerator and takes several minutes to scan a circuit, but Xiao and Schrag are working ____5____.

　　练习：

　　A　to shrink it to the size of a desktop computer and cut the scanning

　　B　to making chips any smaller

　　C　to take tiny chips we require

　　D　to picture the progress of the currents

　　E　converting the information into a color picture showing the density

　　F　faults in the metal strip of a forged banknote or bacteria in a water

　　答案与题解：

　　1.D　manage to+v.是“设法做成”的意思。picture在此是动词，“to picture the progress of the cuixents”意为“绘出电流运行图”。

　　2.E　by在句中引导两个在句法结构上并列的分词短语：一个是measuring subtle changes in the magnetic field of an object，另一个是converting the information into a color picture showing the density of current at each point。convert ... into ... 的意思是“把……转变为……”。

　　3.B　“obstacle to+名词性成分”的意思是“……的障碍”。

　　4.F　faults in the metal strip of a forged banknote和bacteria in a water sample与前文中的microscopic cracks in an aeroplane’s fuselage在意思上是并列的关系。

　　5.A　这部分所说的体积的减小和所需时间的缩短恰好与前半句中提到的冰箱大小的体积和所需数分钟的时间形成了对比。

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（实习编辑：高奕飞）