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Most conducting materials such as copper, aluminum, iron, ni

题目
单选题
Most conducting materials such as copper, aluminum, iron, nickel, and tungsten （）.
A

increase in resistance with increased temperature

B

increase in resistance with decreased temperature

C

decrease in resistance with increased temperature

D

increase in conductance with increased temperature

参考答案和解析
正确答案： A
解析： 暂无解析
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相似问题和答案

第1题：

When placed in a magnetic field, which of the materials listed will maintain the highest permeability?( )

A.Glass

B.Bakelite

C.Soft iron

D.Aluminum


正确答案：C
解析：magnetlc：磁的;permeability：渗透;Bakelite：电木;aluminum：铝
译文：在所列选项中，软铁的导磁率最大。

第2题：

You are carrying cargoes of crotonaldehyde，phosphoric acid，and morpholine on your multiple-product tanker. Which of the following statements is TRUE?

A.Each of the cargoes must be segregated from the other by at least two barriers

B.The minimum protective clothing required for taking samples of phosphoric acid is goggles or a face shield

C.Aluminum，copper，and zinc are prohibited in all valve parts in contact with these cargoes

D.The required warning sign must have the legend "cancer hazard" added to it


正确答案：A

第3题：

Passage Two

Questions 26 to 30 are based on the following passage.

The electromagnet was invented in England by William Sturgeon，who took an iron rod and bent it into the shape of a horseshoe. This “horseshoe” was coated with varnish and a layer of copper wire was wrapped around it. An electric current was passed through the wire，thus making the rod magnetic. The rod was now，because of magnetic attraction，able to support nine pounds of iron. In the US，a scientist named Joseph Henry improved on Sturgeon's electromagnet by insulating the copper wine with silk. He was able to wrap many turns of wire around an iron core without danger of short circuits between the turns. His magnet could hold 2,300 pounds. This experiment prompted Henry to try his hand at converting magnetism into electricity. First he coiled some insulated wire around an iron bar. connecting both ends of the wire to a galvanometer(电流表). The iron bar was placed across the poles of the electromagnet. Then the coil of the electromagnet was connected to a battery. The galvanometer indicated a voltage，then dropped to zero. Henry signaled his assistant to disconnect the coil. The galvanometer showed that once again a voltage had been produced，although this time in the opposite direction. The principle of electromagnetic induction had thus been discovered. Unfortunately for Joseph Henry he did not publish his findings and someone else(Faraday)got the credit for the discovery.

The principle of electromagnetic was discovered by______.

A. William Sturgeon

B. Joseph Henry

C. Faraday

D. someone else


正确答案：B
[解析] 答案见文章最后两句。

第4题：

共用题干
第三篇

Iron Deficiencies

Experts have observed for years that endurance athletes,particularly females,frequently have iron deficiencies.Now a new study by a team of Purdue University researchers suggests that even moderate exercise may lead to reduced iron in the blood of women.
"We found that women who were normally inactive and then started a program of moderate exercise showed evidence of iron loss,"says Roseanne M.Lyle,associate professor at Purdue.Her study of 62 formerly inactive women who began exercising three times a week for six months was published in the journal Medicine & Science in Sports & Exercise."Women who consumed additional meat or took iron supplements were able to bounce back,"she notes."But the new exercisers who followed their normal diet showed a significant decrease in iron levels."
Iron deficiency is very common among women in general,affecting one in four female teenagers and one in five women aged 18 to 45,respectively.But the ratio is even greater among active women,affecting up to 80 percent of female endurance athletes.This means,Lyle says,that"too many women ignore the amount of iron they take in."
Women of childbearing age are at greatest risk,since their monthly bleeding is a major source of iron loss.Plus,many health-conscious women increase their risk by rejecting red meat,which contains the most easily absorbed form of iron.And because women often restrict their diet in an effort to control weight,they may not consume enough iron-rich food,and are liable to experience a deficiency.
"The average woman takes in only two thirds of the recommended daily allowance of iron," notes another expert."For a woman who already has a poor iron status,any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency,"notes the expert. Exercise can result in iron loss through a variety of mechanisms.Some iron is lost in sweat,and,for unknown reasons,intense endurance exercise is sometimes associated with bleeding of the digestive system.
The best sources of iron,and the only sources of the form of iron most readily absorbed by the body,are meat,chicken,and fish.Good sources of other forms of iron include dates,beans,and some leafy green vegetables.

Who will show evidence of iron loss?
A:Inactive women.
B:Active women.
C:Women who do a program of moderate exercises regularly.
D:Women who are inactive and start to do moderate exercises.

答案：D
解析：
文章第一段第一句告诉我们endurance athletes会缺铁，它是指“耐力运动员”。选项A是指“跳高运动员”，选项B是指“举重运动员”，选项C是指“马拉松运动员”，选项D是指“短跑运动员”。因此选项C最合适。
文章第二段第一句话提到“那些通常不运动的女性一旦开始适度的锻炼，就会出现铁含量下降的迹象”。因此只有选项D最正确。
文章第二段最后一句话提到，那些增食肉类食品或服用铁质补剂的女性能够恢复到健康状态。但突然参加锻炼却仍沿用旧食谱的人则显示出铁含量降低。因此只有选项D正确。
文章第三段第一句话告诉我们，每四个十几岁的少女中有一人缺铁，每五个18岁至45岁的女性中有一人缺铁。而在积极锻炼的妇女中这一比例更高，女耐力运动员中，缺铁者比例则高达80%。因此只有选项C表述正确。
文章第四段告诉我们选项A、B、D所指人群都有缺铁的风险，第六段提示我们富含铁的食物中提到了bean和date，因此只有C项是正确的。

第5题：

Foam-type portable fire extinguishers are most useful in combating fires involving ______.

A.solid materials such as wood or bales of fiber

B.inflammable liquids

C.electrical equipment

D.metallic solids


正确答案：B
泡沫型便携式灭火器对于陷于易燃性液体火灾的扑灭最有效。

第6题：

Which of the following materials is a good insulator?( )

A.Steel

B.Aluminum

C.Glass

D.Copper


正确答案：C
解析：insulator：绝缘子;aluminum：铝;copper：铜
译文：玻璃是一种良好的绝缘体。

第7题：

You are on a multiple product tanker and carrying methyl acrylate，diethanolamine，and triethylamine. Which statement is TRUE?

A.Methyl acrylate may be loaded in a tank adjacent to diethanolamine but not triethylamine

B.The heating coils to the cargo tank loaded with methyl acrylate must be blanked off

C.Valve components made of aluminum，copper，or zinc may not be in contact with the cargoes

D.Each crew member working on deck must have an emergency escape breathing apparatus


正确答案：B

第8题：

Why did Sturgeon's electromagnet could support nine pounds of iron?

A. Because the iron rod was bent into the shape of a “horseshoe”.

B. Because the rod was coated with varnish.

C. Because a layer of copper wire was wrapped around the rod.

D. Because the rod was made magnetic by the passing current.


正确答案：D
[解析] 答案见文章第3第4句。电流通过金属丝，使得金属棒带有磁性，由于磁性的吸引，金属棒可以承受9磅的铁。

第9题：

共用题干
第三篇

Iron Deficiencies

Experts have observed for years that endurance athletes,particularly females,frequently have iron deficiencies.Now a new study by a team of Purdue University researchers suggests that even moderate exercise may lead to reduced iron in the blood of women.
"We found that women who were normally inactive and then started a program of moderate exercise showed evidence of iron loss,"says Roseanne M.Lyle,associate professor at Purdue.Her study of 62 formerly inactive women who began exercising three times a week for six months was published in the journal Medicine & Science in Sports & Exercise."Women who consumed additional meat or took iron supplements were able to bounce back,"she notes."But the new exercisers who followed their normal diet showed a significant decrease in iron levels."
Iron deficiency is very common among women in general,affecting one in four female teenagers and one in five women aged 18 to 45,respectively.But the ratio is even greater among active women,affecting up to 80 percent of female endurance athletes.This means,Lyle says,that"too many women ignore the amount of iron they take in."
Women of childbearing age are at greatest risk,since their monthly bleeding is a major source of iron loss.Plus,many health-conscious women increase their risk by rejecting red meat,which contains the most easily absorbed form of iron.And because women often restrict their diet in an effort to control weight,they may not consume enough iron-rich food,and are liable to experience a deficiency.
"The average woman takes in only two thirds of the recommended daily allowance of iron," notes another expert."For a woman who already has a poor iron status,any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency,"notes the expert. Exercise can result in iron loss through a variety of mechanisms.Some iron is lost in sweat,and,for unknown reasons,intense endurance exercise is sometimes associated with bleeding of the digestive system.
The best sources of iron,and the only sources of the form of iron most readily absorbed by the body,are meat,chicken,and fish.Good sources of other forms of iron include dates,beans,and some leafy green vegetables.

Who will have a significant decrease in iron levels?
A:All the women.
B:All the inactive women.
C:Women who start to do moderate exercise and follow their normal diet.
D:Women who start to do moderate exercise and consume additional meat or take iron supplements.

答案：C
解析：
文章第一段第一句告诉我们endurance athletes会缺铁，它是指“耐力运动员”。选项A是指“跳高运动员”，选项B是指“举重运动员”，选项C是指“马拉松运动员”，选项D是指“短跑运动员”。因此选项C最合适。
文章第二段第一句话提到“那些通常不运动的女性一旦开始适度的锻炼，就会出现铁含量下降的迹象”。因此只有选项D最正确。
文章第二段最后一句话提到，那些增食肉类食品或服用铁质补剂的女性能够恢复到健康状态。但突然参加锻炼却仍沿用旧食谱的人则显示出铁含量降低。因此只有选项D正确。
文章第三段第一句话告诉我们，每四个十几岁的少女中有一人缺铁，每五个18岁至45岁的女性中有一人缺铁。而在积极锻炼的妇女中这一比例更高，女耐力运动员中，缺铁者比例则高达80%。因此只有选项C表述正确。
文章第四段告诉我们选项A、B、D所指人群都有缺铁的风险，第六段提示我们富含铁的食物中提到了bean和date，因此只有C项是正确的。

第10题：


According to Paragraph 5，the EEOB’s decoration details( )

A.had almost no cast iron and plaster
B.hardly use of wood for fireproofing
C.are with the materials of granite，bronze，and glass
D.are with carved wood，oriental rugs，and stenciled wall patterns

答案：C
解析：

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