[填空题]Maglev trains are comparable to airplanes in revolutionizing the transportation.

[填空题]Maglev trains are comparable to airplanes in revolutionizing the transportation.

[填空题]Maglev trains can run extremely fast partly because they are free from friction by floating on ______.

[填空题]Japanese maglev trains are different from German ones primarily in ______.

[填空题]
1 A few countries are using powerful electromagnets to develop high-speed trains, called maglev trains. Maglev is short for magnetic levitation, which means that these trains float over a guide way using the basic principles of magnets to replace the old steel wheel and track trains.
2 If you’ve ever played with magnets, you know that opposite poles attract and like poles repel each other. This is the basic principle behind electromagnetic propulsion. Electromagnets are similar to other magnets in that they attract metal objects, but the magnetic pull is temporary. You can easily create a small electromagnet yourself by connecting the ends of a copper wire to the positive and negative ends of an AA-cell battery. This creates a small magnetic field. If you disconnect either end of the wire from the battery, the magnetic field is taken away.
3 The magnetic field created in this wire-and-battery experiment is the simp

[填空题]The engine for maglev trains is used to pull train cars along steel tracks.

[单项选择]Conversation oneWhy are maglev trees free of noise
A. They don’t use rails.
B. They run under water.
C. They travel at high speed.

[单项选择]Conversation oneWhat was the idea of maglev trees firstly invented
A. B．In the US
B. C．In the U.

[填空题]Steam trains gave _____ to electric trains soon after the war.

[填空题]The maglev line plan from Los Angeles to Pittsburgh has been suspended because of its high ______.