单项选择题

Radio signals will take () to reach the next star.

A．25 years
B．50 years
C．hundreds of years
D．a few years

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热门试题

单项选择题

People always thought about the question, ()

A．"How can scientists use machines to look for a star"
B．"How far away are the stars"
C．"How many years a person would take to go to the next star in a spaceship"
D．"Is there life in space"

单项选择题

The speed of radio signals is ()a spaceship.

A．a little greater than
B．as great as
C．much greater than
D．less than