题目

完形填空阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。 Youth sports teach kids to develop a winning state of mind as well as the ability to become team leaders. Although having 1 is a major part of athletics, the only purpose of sports is to compete and create the 2 mentality (心态) people need in sports.3 have the extremely hard task of getting their young athletes to learn how to play the sport and become disciplined, and ready to play the sport to the best of their a一个物体在两个力作用下处于平衡状态，那么A.物体受到的合力一定为零B.物体的运动状态一定保持不变C.物体的重力势能一定保持不变D.物体的机械能一定保持不变