下列相关物理知识的说法，正确的是_刷题宝

题干

下列相关物理知识的说法，正确的是（　　）

A：菜刀的刀做得很薄主要目的是为了节省材料

B：旗杆项端安装一个定滑轮是为了省力

C：飞机的机翼做成上凸下平是为美观

D：给滚动轴承加润滑油是为了减小摩擦

上一题下一题 0.0难度选择题更新时间:2017-08-15 12:01:24

答案(点此获取答案解析）

D

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完形填空。

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