请回答下列问题:
A. It's time for Chinese class. B. It's time for lunch.
C. It's time for school. D. Time to go home.
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①统一度量衡、货币
②车同轨,书同文
③焚书坑儒
④建立了统一国家
⑤开创了皇帝制、郡县制和中央集权制
⑥开创了科举制
⑦修筑万里长城、开凿灵渠