单选题
According to the passage, "weight" should be understood in the sense that
A、
it is fixed if it is outside the earth's gravitational pull.
B、
it decreases four times when it is 4,000 miles from the earth's center.
C、
it varies with the change of the gravitational attraction between two objects.
D、
things increase in amount as they are closer to the earth's surface.
【正确答案】
C
【答案解析】
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