单项选择题

What is the distance between the Earth and the two areas of radiation

A．Between 12 and 21 miles.
B．1,000 miles.
C．150 miles.
D．1,500 miles.
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单项选择题
What forms of radiation are feared by astronauts
A．Radiation from the sun.
B．Radiation from the Van Allen Belts.
C．Radiation from the meteors.
D．Both A andB.
单项选择题
In the author's opinion, why do we search the stars or moon
A．Because we have made up our mind to do so.
B．Because we want to fulfil our desire for knowledge.
C．Because we want to enjoy the ecstasy of achievement.
D．Because we cannot help ourselves.
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