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

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问题:

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

考点:摩擦力的大小摩擦力的种类杠杆的平衡条件
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患儿,8个月,因夜间睡眠不安、多汗、易激惹就诊,体检可见患儿有方颅、肋膈沟,镯征、足镯征。

该患儿应诊断为()。

A.佝偻病初期

B.佝偻病激期

C.佝偻病后遗症期

D.营养不良

E.骨软化病

题型:选择题

下列说法正确的有[ ]

A.光电子的最大初动能和照射光的频率成正比

B.大量光子的效果往往表现出波动性,个别光子的行为往往表现出粒子性

C.卢瑟福用α粒子散射的实验数据估算原子核的大小

D.玻尔的原子模型彻底否定了经典的电磁理论

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Most of us are taught to pay attention to what is said--the words. Words do provide us with some information, but meanings are (1) from so many other sources that it would hinder our effectiveness (2) a partner to a relationship to rely too heavily on words (3) Words are used to describe only a small part of the many ideas we associate with any given (4) . Sometimes we can gain insight into some of those (5) if we listen for (6) words. We don’t always say what we mean (7) mean what we say. Mostly we mean several things at once. A person wanting to purchase a house says to the current owner. "This step has to be fixed before I’ll buy." The owner says, "It’s been like that for years". (8) , the step hasn’t been like that for years, but the (9) message is: "I don’t want to fix it. We can put up with it why can’t you" The (10) for a more expansive view of meaning can be developed by examining a message (11) who said it, when it occurred, the (12) conditions or situation, and how it was said.

When a message occurs can also (13) associated meaning. A friend’s unusually docile behavior may only be understood by (14) that it was preceded by situations that required a (n) (15) amount of assertiveness.

We would do well to listen for how message are (16) The words, "it sure has been nice to have you over," can be said with (17) and excited or ritualistically. The phrase can be said once or (18) several times. And the meaning we associate with the phrase will change (19) Sometimes if we say something infrequently it assumes more importance; sometimes the more we say something the (20) importance it assumes.

Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C, and D on ANSWER SHEET 1.4()

A.message

B.description

C.statement

D.explanation

题型:选择题

如何进入文书申请审批作废窗口?

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油压减振器的减振性能与()因素无关。

A.机车的运行时间

B.油压减振器内节流孔大小

C.油压减振器内的活塞面积

D.油压减振器的油液粘度

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