下列物质属于纯净物的是( ) A.钢 B.煤 C.冰水混合物 D.洁净的空气

题型:选择题

问题:

下列物质属于纯净物的是(  )

A.钢

B.煤

C.冰水混合物

D.洁净的空气

考点:纯净物和混合物
题型:选择题
     短文改错。
     文中共有10处语言错误,每句中最多有两处。
     错误涉及一个单词的增加、删除或修改。
     增加:在缺词处加一个漏字符号(∧),并在其下面写出该加的词。
     删除:把多余的词用斜线(\)划掉。
     修改:在错的词下划一横线,并在该词下面写出修改后的词。 
     注意:每处错误及其修改仅限一词。只允许修改10处,多者(从第11处起)不计。
     Peter was a small boy. He lived in with his parents in a small house near some hills. People there were 
both poor. One night it was very dry and windy. When everybody was asleep, Peter sudden heard some 
noise. It came out from the kitchen. He got up and walking to the kitchen. He found that the wood
 besides the stove was burning. There was no water tap in the house, but he could not put out the fire. He 
shouts loudly to wake up everyone in the house. Then she ran out of his house and knocked at the doors 
of many houses to wake people up. They all left their house quickly. At last the fire was put out the 
firemen. Many houses were burnt. But nobody was burnt in the fire.
_______________________________________________________________________________
题型:选择题

铅笔每枝a元,买了m枝,付出b元,应找回______元.

题型:选择题

“更高、更快、更强”的奥运精神在化学学习中有所体现。请分析题意,按要求回答问题:

(1)写出右下图实验一中“更高”的化学方程式:                              。由此实验你认为实验室除去混合气体中的二氧化碳气体杂质的最佳试剂是          

(2)写出右图实验二中“更快”的化学方程式:                        

(3)“更强”,辩论见风采。某学校化学兴趣小组的同学准备了一场辩论赛。辩论主题是“1 + 1等于不等于2。”甲方认为:1 + 1等于2。乙方认为:1 + 1不等于2。请根据溶液的相关知识判断。

①如果你认为甲方正确,请举一例                                           

②如果你认为乙方正确,请举一例                                           

题型:选择题

2011年4月1日,甲公司签订一项承担某工程建造任务的合同,该合同为固定造价合同,合同金额为780万元。工程自2011年5月开工,预计2012年4月完工。至2011年12月31日止甲公司累计实际发生成本为656万元,结算合同价款300万元。甲公司签订合同时预计合同总成本为720万元,因工人工资调整及材料价格上涨等原因,2011年年末预计合同总成本为820万元。假定甲公司采用累计实际发生的成本占预计总成本的比例计算确定完工进度,2011年12月31日甲公司对该合同应确认的预计损失为( )万元。

A.40
B.100
C.32
D.8

题型:选择题

   It is midnight on September 22, 2012. The sky above Manhattan,New York is filled with a curtain of colorful light. New Yorkers are fascinated by the beautiful aurora (极光). However, their fascination is short-lived.

Within a few seconds, electric bulbs dim and flicker (闪烁), then become unusually bright for a few seconds. Then all the lights go out. Within 90 seconds, the entire eastern half of the US is without power.

Besides the US, Europe, Japan and China are also hit by the same terrible event. It is a violent solar flare (太阳耀斑) ,150 million kilometers away on the surface of the sun.

Science fiction? No. A report funded by NASA and issued by the US National Academy of Sciences in January this year says it could happen.

A massive solar flare is most likely on a spring or autumn night in 2012, according to the report.

Solar flares are huge explosions on the surface of the sun. In a matter of just a few minutes they heat material to many millions of degrees and release as much energy as a billion megatons (百万吨) of TNT explosives. Solar flares release a stream of charged high-energy particles (粒子). They are called “solar winds”.

If one solar “wind” should hit the Earth’s magnetic shield (磁场), the result could be terrible for humans.

But there’s no need to run for cover from solar winds. They do not harm life on Earth, they only affect the way we live, especially since we depend so much on modern technology. They can pump extra electricity into power lines and pipelines, causing blackouts and fuel leaks. Solar winds are also known to affect mobile phone operations and may disrupt wireless Internet services.

Moreover, solar winds can prevent normal satellite operations, and disrupt radio communications and navigation systems such as the Global Positioning System.

Auroras are powered by solar wind. This wind blows past the Earth at about 400-700 km per second and creates storms in the Earth’s magnetic environment. In the polar regions these explode into southern or northern polar lights.

The most serious solar storm that hit Earth in history happened in 1859. It caused the failure of telegraph systems in Europe and North America.

So, for humans, the sun is a double-edged sword. Without the sun, there would be no life on Earth. Without the sun, Earth would be a frozen dark ball floating in space. However, on the other hand, the sun can disorder our lives from time to time.

56. What is the main idea of the passage?

A. It introduces to readers the advantages and disadvantages of the sun.

B. It describes a science fiction set in Manhattan on 22 September 2012.

C. It shows readers the way in which solar winds form inside the sun.

D. It explains what solar flares are and their effects on human life.

57. The first two paragraphs are written ____.

A. to show a beautiful scene in a true story

B. to describe the beautiful scenery of Manhattan

C. to describe the power problem around the world

D. to introduce the topic of this passage

58. What can we conclude from the passage?

A. Solar flares will do great harm to those who are using the Internet.

B. Solar flares cannot reach as far as the polar regions.

C. Solar flares are huge explosions that happen inside the sun.

D. But for our reliance on technology, solar flares wouldn’t

affect us so much.

59. Solar winds will likely affect us in the following ways EXCEPT that ____.

A. normal satellite operations will be stopped

B. the lights in the areas affected will go out at the same time

C. people on the streets will be struck to death

D. some navigation systems will be out of order

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