问题
单项选择题
皮带正常工作时，皮带与皮带轮之间产生（）。
A.滑动摩擦力；
B.静摩擦力；
C.最大静摩擦力；
D.滚动摩擦力
答案
参考答案：B
搜题请搜索小程序“爱下问搜题”
皮带正常工作时，皮带与皮带轮之间产生（）。
A.滑动摩擦力；
B.静摩擦力；
C.最大静摩擦力；
D.滚动摩擦力
参考答案：B
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| Tom lives in New York. His father has a shop and his mother is a doctor. He is seven years old now, and begins 1 to school this autumn. It's far 2 from their shop and his father 3 him to school every day. So he 4 never late for school and his teachers all like him. It's Monday today, Miss Hunt is teaching them to 5 from one to ten. Sam is studying hard. Soon he can count 6 . Miss Hunt is happy and 7 , "How many people are there in your 8 , Sam?" Sam stands up and says, "Two, Miss Hunt." " 9 ''are they?" "My father and my mother." "Oh?" Miss Hunt is surprised. She says, " There are three people in your family." "But now I am not 10 . I am at school, you know!" | ||||
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