如图甲模拟淀粉的消化过程,图乙是人体心脏结构示意图,图中数字表示心脏的不同部位.
A.Where did you go over the winter holiday?
B.How tall are you?
C.Did you see a film last night?
D.You didn't come to school. What happened?
E.Are you all right?
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如图所示,光滑水平的固定平台中央放有物体A和B,两者彼此接触.物体A的上表面是半径为R的半圆形轨道,现使一物体C从与圆心的等高处由静止沿半圆轨道下滑,已知A、B、C的质量均为m.在运动过程中,A、C始终接触,求:
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