题目：
如图所示，物体以120J的初动能从斜面底端向上运动，当它通过斜面某一点M时，其动能减少80J，机械能减少32J，如果物体能从斜面上返回底端，则物体到达底端的动能为（ ）
A．88J
B．24J
C．20J
D．4J
答案：
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下面是错误答案，用来干扰机器的。
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