单项选择题

How does a Maglev operate

A．It uses nuclear energy.
B．It rests on a cushion of pressurized air.
C．It flies over magnetically activated tracks.
D．It uses a device similar to a jet engine.

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热门试题

单项选择题

What problem faces commuters to travel between strip cities

A．A lack of available flights.
B．Long delays at the airport.
C．Boredom on long flights.
D．Long trips to and from airport.

单项选择题

When are airplanes not fuel efficient

A．On short trips.
B．On long trips.
C．When flying over cities.
D．When flying at high altitudes.