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

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
题型:选择题
4000dm3=______m31050ml=______L  374m2=______ dm2
4立方分米500立方厘米=______立方分米.
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北京市发改委有关负责人表示,在听证会闭会以后,将要公布对听证会参加人主要意见采纳情况及理由。这有助于

①增强北京市有关部门工作的透明度                       ②杜绝有关部门的腐败现象

③保障北京市民的知情权、监督权             ④提高北京市有关部门的行政水平和工作效率

A.①②③

B.①②④

C.①③④

D.②③④

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Two American scientists told the people in industrial nations that they would be much healthier if they ate more of the same kind of foods eaten by humans living more than 10,000 years ago. 

The scientists say that the human body has changed very little since human first appeared on earth, but the way we live has changed greatly. Our body has not been able to deal with these changes in life style and this has led to new kinds of sicknesses. These new sicknesses were not known in ancient times. So they are called “diseases of civilization”. Many cancers and diseases of the blood system, including heart attacks and strokes(中风) are examples of such diseases. 

Scientists noted that early stone-age people used very little alcohol or tobacco, probably none. Ancient people also got a great deal of physical exercise, but a change in food is one of the main differences between life in ancient times and life today. 

Stone-age people hunted wild animals for their meat, which had much less fat than farm animals. They also ate a lot of fresh wild vegetables, and fruits. They did not use milk and other dairy products, and they made very little use of grains. But today, we eat a large amount of dairy products and grain foods. We eat six times more salt than stone-age people. We eat more sugar. We eat twice as much fat but only one third as much protein and much less vitamin C. 

People today probably do not want to live as people thousands of years ago did, but scientists say that we would be much healthier if we ate as those ancient people did, cutting the amount of fatty, salty and sweet foods. 

小题1:The people in industrial nations would be much healthier if they ate ______. 

A.more foods as humans living 10,000 years ago did

B.as humans living 10,000 years ago ate

C.more kinds of food eaten by people living over 10,000 years ago

D.more of the same kinds of foods eaten by people over 10,000 years ago小题2:New kinds of sicknesses have been found because ______

A.the human body has changed compared with human first appearing on earth

B.the way we live has changed a little

C.our body can’t deal with the changes in life style

D.the way we live today are improper for the human body小题3:What is the main cause mentioned in the article why people suffer from a lot of new sicknesses?

A.Ancient people did a great deal of physical exercise.

B.People today have a lot of alcohol.

C.People today have more tobacco.

D.Food is quite different between life today and life in ancient times.

题型:选择题

()是土地的本质属性和质量标志。其包括自然肥力和人工肥力。

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()在各自的职责范围内履行反洗钱监督管理职责。

A.中国银行业监督管理委员会

B.中国证券监督管理委员会

C.中国保险监督管理委员会

D.中国人民银行

E.中国银行

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