有关血液循环的说法，正确的是（）。
A.大循环先开始
B.大循环开始于右心室
C.小循环终止于右心房
D.小循环动脉内含有静脉血
参考答案：D
_____, you need to give all you have and try your best. [ ]
A. Being a winner
B. To be a winner
C. Be a winner
D. Having been a winner
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