题目

小东在体育课上做单杠练习时，两臂伸直，双手平行握住单杠，之后逐渐增加双手间距，此过程中手臂上的拉力变化情况为（                                                                                                            ）                                                                                                               　   A． 逐渐变小               B．逐渐变大     C． 先变大后变小       D． 先变小后变大                                                                                                                               答案：B

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