问题 实验题

某同学在实验室测量一块不规则的金属块的密度。

(1)把托盘天平放在水平桌面上,将游码移至标尺左端零刻线处.观察到横梁指针指在分度盘中线的左侧,此时应向                        旋动平衡螺母。

(2)把金属块放在左盘,用镊子向右盘加减砝码后,观察到横梁指针的位置如图甲所示,此时应该调节                ,直到指针再次指在分度盘中线处.游码的位置和右盘中的砝码如图乙所示,金属块的质量是                g。

(3)把金属块浸没在装有50mL水的量筒中,这时量筒中的水面的位置如图丙所示.金属块的密度为                       kg/m3

答案

(1)右;

(2)游码;54;

(3)2.7 ×103

阅读理解

阅读理解

     Beijing had its biggest snowfall since 1951.Britain is suffering through its longest cold snap (寒潮) since

1981.And freezing weather is hitting the Deep South,including Florida's orange groves and beaches.

     Whatever happened to global warming?

     Such weather doesn't seem to fit with warnings from scientists that the Earth is warming because of

greenhouse gases. But experts say the cold snap doesn't contradict  global  warming at all-it's just a

temporary phenomenon  in  the  longterm heating trend."It's part of natural variability," said Gerald Meehl,

a senior scientist.With global warming,he said,"we'll still have record cold temperatures.We'll just have

fewer of them."

     Scientists say manmade climate change does  have the  potential to cause more frequent and  more

severe weather extremes.But experts did not connect the current cold snap to climate change.

     So what is going on?

     " We  basically have seen just a big outbreak of  Arctic air over populated areas of the Northern

Hemisphere",Arndt said.

     In the atmosphere,large rivers of air travel roughly west to east around the globe between the Arctic

and the tropics.This air flow acts like a fence to keep Arctic air restricted.But recently,this air flow has

become bent into a zigzag  (之字形)  pattern,wandering north and south.If you live in a place where it

brings air up from the south,you get warm weather. In fact, record  highs were reported this week in

Washington state and Alaska.

     But in the eastern United States,like some other unlucky parts of the globe,Arctic air is coming from the north. And  that's how you get a  temperature of 3 degrees in Beijing, a reading of  minus 42 in mainland

Norway,and 18 inches of snow in parts of Britain.The zigzag pattern arises naturally from time to time,but

it is not clear why it's so strong right now.

1.What is the best title of the text?

A.Freezing weather is hitting the Deep South

B.We'll still have record cold temperatures

C.The air flow has become a zigzag pattern

D.Cold snap doesn't contradict global warming

2.With global warming,we will________.

A.also meet with severe cold snap

B.have more hot temperatures forever

C.never experience cold temperatures

D.have more cold temperatures

3.According to experts,the current cold snap________.

A.suggests that the climate has changed greatly

B.is not related to the climate change

C.shows that the climate will turn cold

D.is affected by global warming

4.Beijing had its biggest snowfall since 1951 because of________.

A.a fence from the Arctic  

B.a cooling trend in climate

C.a big outbreak of Arctic air  

D.its large population

5.We can conclude that________.

A.not all the parts of the Northern Hemisphere are cold in face of the cold snap

B.the zigzag pattern arises naturally accidentally

C.Beijing will get cold weather next year

D.Washington state and Alaska will not face cold weather next year