图示为儿童蹦极的照片，儿童绑上安全带，在两根弹性绳的牵引下上下运动．在儿童从最高点下降到最低点的过程中_刷题宝

题干

图示为儿童蹦极的照片，儿童绑上安全带，在两根弹性绳的牵引下上下运动．在儿童从最高点下降到最低点的过程中（　　）

A：重力对儿童做负功

B：合力对儿童做正功

C：儿童的重力势能减少

D：儿童的机械能守恒

上一题下一题 0.0难度选择题更新时间:2016-05-23 12:24:18

答案(点此获取答案解析）

C

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