题目内容
A Train Floating On Air
A train that floats on air ? It’s not magic—it’s magnets ( 磁 ) . And it’s close to reality .
In Virginia USA the fall of 2002 a train with no wheels traveled on air and carried college students across their campus . In Japan , a whisper-quiet railway engine hovered and raced at 350 miles per hour using magnets and electricity as the power . And in China , a magnet train line linked Shanghai with nearby Pudong Airpot .
These trains use magnetic levitation ( 悬浮 ) technology , “ maglev ” for short , They use the same rules as the magnets you pick up at home or school : opposite poles of magnets attract each other , and like poles repel each other .
How does it work ?
Powerful magnets on the bottom of the train repel magnets on the track , which is actually just a magnet-filled guiding way . With a magnetic field of sufficient force , the train will go hovering on air , which seemed impossible to us in the past .
When an electrical current is sent through the track , the train moves . Turn the current backwards and the train slows down .
Maglev doesn’t rely on the friction (摩擦力) of wheels on track , so it can climb a much steeper hill than a traditional train . And it can travel easily in snow and ice , something that could bring normal trains to a screaming stop .
1．This passage is about _______
A．maglve B．magnets C．levitation D．electricity
2．Which of the following is a repelling action ?
A．
B．
C．
D．
3．What can we learn from the text ?
A．A magnet-filed guiding way is formed inside a maglev train .
B．Instead of electricity , magnets are used as the power of a maglev .
C．Maglev trains can climb hills with the help of magnet wheels .
D．Electric currents decide the movements of a maglev train .
4．What is the difference between a maglev train and an ordinary train ?
A．A maglev train can climb mountains without power while an ordinary one can’t
B．A maglev train can travel in college campus while an ordinary train is not allowed
C．Travelling without a track , a maglev train is safer and smoother than an ordinary one
D．Floating on a track , a maglev train is faster , quieter than an ordinary railway train .
1．A 2．B 3．D 4．D
