单选题
According to the passage, when could people start using a maglev commercially?
A) In 5 years. C) In 20 years.
B) In 10 years. D) In more than 20 years.
A、
According to the passage, when could people start using a maglev commercially?
B、
In 5 years.
C、
In 10 years.
D、
In 20 years.
E、
In more than 20 years.
【正确答案】
B
【答案解析】
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