题目内容:
Paragraph 6 _____
A.The Main Components of the Maglev Train System B.High-speed Maglev due to Zero Friction
C.The Working Principle of the Maglev Train
D.Differences between Polarity and Magnetic Field
E.Comparison of Maglev Trains with Traditional Ones
F.Maglev with a Powerful Motor
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答案解析: