Question

Cloud seeding is a method of artificially causing clouds to produce precipitation （降水） in the form of rain or snow．Cloud seeding has also been used in attempts to modify the severity of hail storms and hurricanes．The effectiveness of cloud seeding remains controversial （有争议的）．but it continues to be used in some regions to try to increase rainfall for agriculture and to build snow packs for water supplies and power production．

Cloud seeding was developed by American scientists Irving Langmuir and Vincent Joseph Schaefer during and after World War II．Their work began as an effort to learn more about the buildup of ice on airplane wings, and eventually led them to attempt to create rainfall by releasing several pounds of crushed frozen carbon dioxide into a cloud from an airplane．In this form, the carbon dioxide is called dry ice．On November 13, 1946, the technique appeared to produce snow directly under the cloud; the snow then turned to rain as it fell to the ground．

For their experiment, Langmuir and Schaefer selected a supercooled cloud, one in which the water droplets remain liquid in subfreezing temperatures．Their theory was that small grains of dry ice falling through the cloud would cause tiny droplets of water vapor in the cloud to freeze into crystals that attracted more water vapor．Their theory proved to be correct and eventually the crystals became heavy enough to fall from the cloud as snow．As the snow reached the warmer temperatures closer to the ground, it melted and became rain．

Another scientist, Bernard Vonnegut, produced a method of cloud seeding using silver iodide （碘化银）．He used particles of silver iodide because its crystal structure resembled that of ice in clouds．Silver

iodide also had practical advantages over frozen carbon dioxide It could be stored at room temperature

and did not require an airplane as a delivery mechanism．Instead, silver iodide crystals could be fired by

cannons （大炮） high into the air, where wind carried them into the clouds．

1.According to the text, Langmuir and Schaefer had intended to deal with__

A．how to freeze carbon dioxide??????????????????????

B．how to remove ice on plane wings

C．how to make weather forecast for the war?????????????

D how to hide planes in clouds at war

2.What is the CORRECT order of the course for cloud seeding with dry ice?

a．snow becoming rain in wanner temperatures???????????? b．crystals attracting more water vapor

c．crystals falling in the form of snow???????????????????? d．crystals becoming very heavy

e．freezing tiny droplets of water vapor into crystals

f．putting small grains of dry ice in the cloud

A．a-c-f-d-b-e??????????????? ????????????? B．b-f-e-a-c-d????????????

C．f-e-b-d-c-a??????? ????????????? D．e-a-d-c-b-f

3.Bernard chose silver iodide as a method of cloud seeding because___．

A．it is much cheaper than dry ice?????? ????????????? B．it can be stored at any rooms

C．it can be sent into clouds by wind?? ????????????? D．it is similar

4.The best title for the passage may be "____"．

A．Cloud Seeding?????? ?????????????

B．Artificial Raining???????

C．Weather Changing

D．Cloud Gathering

5.How many methods of cloud seeding are mentioned in the passage?

A．three ????????????? B．two?????? ????????????? C．one????????????? D.four

 

Answer 1

【答案】

1.B

2.C

3.D

4.A

5.B

【解析】

试题分析：文章介绍了催化云的方法的发明和云催化的两种方法（干冰和碘化银），还有具体的过程。

1.细节题：从文章第二段的句子：Cloud seeding was developed by American scientists Irving Langmuir and Vincent Joseph Schaefer during and after World War II．Their work began as an effort to learn more about the buildup of ice on airplane wings,可知Langmuir和 Schaefer 本打算处理飞机机翼上的冰。选B

2.细节题：从文章第三段的句子：Their theory was that small grains of dry ice falling through the cloud would cause tiny droplets of water vapor in the cloud to freeze into crystals that attracted more water vapor．Their theory proved to be correct and eventually the crystals became heavy enough to fall from the cloud as snow．As the snow reached the warmer temperatures closer to the ground, it melted and became rain．

可知用干冰催化的云的过程是：f．将干冰射入云层，e．将小的雨滴变成晶体b．晶体吸引更多的水， d．晶体变得更重，c．晶体以水的形式落下，a．在温暖的天气下雪变成雨，选C

3.细节题：从文章第四段的句子：He used particles of silver iodide because its crystal structure resembled that of ice in clouds．可知Bernard用碘化银催化云的方法因为它们很相似，选D

4.标题确定题：从文章的内容和第一段的句子：Cloud seeding is a method of artificially causing clouds to produce precipitation （降水） in the form of rain or snow．可知这篇文章讲的是云的催化。选A

5.细节题：从文章第三段和第四段的内容：可知提到两种催化云（干冰和碘化银）的方法，选B

考点：考查科普类短文