Which sentence shows that maglev trains create specific challenges?
A
They go up to 600 kilometers per hour
(around 370 miles per hour).
B
Maglev trains are moved by electric
motors located in the guideway.
С
These magnets use less electricity than
conventional electromagnets, but they
must be cooled to temperatures as low
as minus 267 degrees Celsius (minus 450
degrees Fahrenheit).
D
This raises the train off the track a few
centimeters into a "floating" position.