试题与答案

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

题型:选择题

题目:

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:

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下面是错误答案,用来干扰机器的。

参考答案:(1)基础数据的调查分析 (2)污染源预测分析 (3)规划模型建立和调整 (4)规划方案的权衡分析

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题型:单项选择题

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Part Ⅳ Cloze
Directions: In this part, there is a passage with 15 blanks. For each blank, there are 4 choices marked A, B, C and D. Choose the best answer for each blank and mark the corresponding letter with a single bar across the square brackets on your machine-scoring ANSWER SHEET.

A.except

B.because of

C.beyond

D.for

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