问题 选择题
如图所示,AB是一质量为m的均匀细直杆,A端靠在光滑的竖直墙壁上,B端置于水平地面上,杆身与竖直方向夹角为θ,杆与地面的摩擦系数为μ,保持平衡,则此时杆与地面的摩擦力为(  )

A.mgtgθ

B.mgsinθ

C.μmg

D.μmg

答案

答案:A

材料题

阅读材料回答问题

现代化的世界进程是人类文明形态的重大飞跃,也是人类社会从分散的地域性历史向整体的世界历史发展的转折。现代化的进程是工业文明向全球扩展的过程。——高中历史高中三年级(实验本)

请回答:

(1)现代化的进程发端于哪个地区?又是如何扩展的?

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(2)现代化的起点发生在哪个国家的什么事件?

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(3)结合材料和所学知识谈谈你对现代化的世界进程的看法。

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单项选择题