It is difficult to determine what caused copernicus to overthrow the fourteen-hundred-year-old ptolemaic theory . 很难断定什么原因使Copernicus抛弃了有1400年之久的Ptolemaic理论。
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It is difficult to determine what caused copernicus to overthrow the fourteen-hundred-year-old ptolemaic theory 很难断定什么原因使copernicus抛弃了有1400年之久的ptolemaic理论。