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问题 选择题

如图所示，质量为2kg的物块在水平面上向左运动，已知物块与水平面间的摩擦因数为0.4，当物块受大小为6N、水平向右的力F作用时，物块的加速度为(     )

A．大小为4m/s2，方向向右

B．大小为3m/s2，方向向左

C．大小为7 m/s2，方向向右

D．大小为7 m/s2，方向向左

答案

答案：C

根据受力分析，利用牛顿第二定律：  代入数据，a=7 m/s2方向向右，故C对。

补全对话，情景问答
完成下面的对话。
a. They're too expensive.
b. I like brown.
c. How much are they?
d. Yes. I'd like to buy a pair of shoes.
e. No. I don't like the colour.
A: May I help you?
B: 1.             
A: These shoes are nice. Would you like them?
B: 2.             
A: What colour do you like?
B: 3.            
A: Do you like these shoes? These shoes are brown.
B: 4.            
A: They're 100 yuan.
B: 5.            
A: What about these shoes. These shoes are on sale. They are only 50 yuan.
B: I'll take one pair of these shoes.
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单项选择题

出现医院感染流行趋势时，医院感染管理科必须于多长时间内报告主管院长医务部，并通报相关部门（）

A.8小时

B.12小时

C.24小时

D.36小时

E.48小时
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