如图所示，一半径为R、质量为M的1/4光滑圆弧槽D，放在光滑的水平

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问题选择题

如图所示，一半径为R、质量为M的1/4光滑圆弧槽D，放在光滑的水平面上，有一质量为m的小球由A点静止释放，在球沿圆弧下滑到B点的过程中，下述说法正确的是

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A．小球的机械能守恒

B．小球和槽组成的系统机械能守恒

C．小球、槽和地球组成的系统机械能守恒

D．小球、槽和地球组成的系统机械能不守恒

答案

答案：C

听力题

根据汉语提示或首字母提示，在每个空格内填入一个适当的英语单词。（每空只填一词）

小题1:A of stealing the car, the man burst into tears.

小题2:If he can support himself, he is i of his parents.

小题3:People with high EQ have p attitude towards life.

小题4:There is no p that we will give in to the Japanese government on Diaoyu Islands.

小题5:I think the question d further discussion.

小题6:I turned round and kept (瞪着) at the man who was bothering me.

小题7:The news that Lin Dan held a great wedding ceremony has been (证实).

小题8:Why should I say sorry when it’s not my f ？

小题9:It’s still not possible to accurately (预测) the occurrence of an earthquake.

小题10:The (账目) show we have spent more than we received.

判断题

直流电机的电枢绕组和换向器片脱焊，会引起电机振动。