问题
单项选择题
Why does the Earth show almost no signs of having been hit by numerous meteors in the past
A．Humans have built over most of the craters.
B．Most meteors fell into the ocean and not on land.
C．The Earth's magnetic field repelled most meteors.
D．The Earth's natural geologic activity has eliminated most traces.
答案
参考答案：D
解析：[分析] 推断题型。 见文中倒数第二句：The planet's active geological processes have left no evidence of the ancient pelting it almost certainly received soon after it was formed．地球活跃的地质作用使得地球从其形成之时起就没留下以往那些曾遭受撞击的痕迹。由此得知以往那些曾遭受撞击的痕迹是由于地球自然的地质作用而消除的，因此答案为D。