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单选题The gap in the ozone hole over the North Pole can expand each summer enough, that it exposes regions as far south as Sweden by heightened UV radiation, also increasing rates of skin cancer in the northern regions by as much as 50 percent.A that it expo

题目
单选题
The gap in the ozone hole over the North Pole can expand each summer enough, that it exposes regions as far south as Sweden by heightened UV radiation, also increasing rates of skin cancer in the northern regions by as much as 50 percent.
A

that it exposes regions as far south as Sweden by heightened UV radiation, also increasing

B

that regions as far south as Sweden have been exposed to heightened UV radiation, as well as having increased

C

to expose regions as far south as Sweden to heightened UV radiation, increased

D

to expose regions as far south as Sweden to heightened UV radiation and increase

E

that exposure to heightened UV radiation in regions as far south as Sweden, as well as increasing

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相似问题和答案

第1题：

When it is winter in China, ______.

A. the USA is tilted toward the sun B. the South Pole is tilted away from the sun

C. the North Pole is tilted toward the sun D. the North Pole is tilted away from the sun


正确答案：D

第2题：

共用题干
Sunbath and Skin Cancer
In the summer,millions of Americans will offer up their bodies to the sun rays.A tan mndi-cates health and beauty,and most sun worshippers will sacrifice a lot to achieve it,including themselves.
With each hour, the sun's ultraviolet radiation (紫外线）produces irreversible（不可逆的） damage,hastening the development of unsightly wrinkles.And with each year on the beach or roof-top,the sunbather increases his risk of getting skin cancer. Skin cancer is by far the most common form of cancer. An estimated 400,000 new cases will be detected this year in the United States, and almost all of them can be blamed on over-exposure to the sun.
Fortunately,most of these cancers are highly curable .But they can he disfiguring and take time to treat. For that reason,sun worshippers should treat deity with a good deal of awe（敬畏）. Sunburn,of course,is the initial hazard posed by UV radiation.Prolonged exposure to UV,howev-er , interferes with the production of collagen fibers（胶原纤维）in the dermis（真皮层）, causing the skin to lose elasticity（弹性）and creating premature wrinkles. Further deterioration（恶化）of the dermis deprives the epidermis（表皮层）of nutrition and causes it to become thin and dry.
Cancer is UV's final result.Shortwave radiant energy,especially from the UV-B band,breaks the strands（股、缕）of DNA. Enzymes（酶）work constantly to rearrange the DNA into proper Se-quence,but with repeated UV exposure,the repair process may eventually break down.Then the mutant（变异的）DNA may produce a colony of cancer cells. But skin cancer may be avoided with a good dose of common sense.People with fair skin and blue eyes who burn easily stand the high-est risk .Special danger spots are the parts of the body most constantly exposed to the sun,such as the cheeks , nose , lower lip and the ears. People who have already developed precancerous（癌变前的）lesions（伤害）or had one skin-cancer growth stand a greatly increased chance of developing others.
Dermatologists（皮肤科医生）recommend avoiding the sun when it is most intense between 11 a.m.and 3 p.m.Anyone who insists on sunbathing should use a good sun screen.These lotions and salves（药膏）contain chemicals that block out the burning UVB radiation while permitting the tanning rays to reach the skin.

The underlined word“deity”in the third paragraph refers to________.
A: something mysterious
B: the skin cancer
C: the sun
D:over-exposure to the sun

答案：C
解析：
在读题时应抓住“over-exposure”一词，在第二段的最后一句“… and almost all of them can be blamed on over-exposure to the sun. ” A项“皱纹”和D项“健康美”都是一般的暴硒引起的而非过度暴硒引起。C项“不惜一切代价”跟过度暴硒没有因果关系。


由第三段可知，皮肤癌即使被治愈，但患者的容貌有可能受损，而导致皮肤癌的正是太阳光，因此可以推断人们应该躲避的是阳光（太阳），而不是皮肤癌。同时，原文是“ treat deity with a good deal of awe（敬畏）”一般是时待神灵才是“满怀敬畏”，而西方传说中太阳也是一位神灵，即太阳神。综上所述，可以推断本题选C。


在文章第三段的第四句“Sunburn , of course , is the initial hazard posed by UV radia-tion.”皮肤变黑实际上是红外线辐射对人体产生的最初危害。先是硒黑，接下来才是真皮受损、失去弹性，损伤表皮。


答案在第四段的第三、第四句“Enzymes(酶) work constantly to rearrange the DNA into proper sequence,but with repeated UV exposure,the repair process may eventually break down. Then the mutant（变异的）DNA may produce a colony of cancer cells.”长时间的暴硒造成修复过程崩溃，并有可能导致癌细胞产生。


其实只要抓住“Dematologists（皮肤科医生）recommend”“avoiding the sun”“ sun screen”“block out”等关键词就能理解最后一段讨论如何预防皮肤癌。

第3题：

The () between the rich and poor regions is being bridge.

A、space

B、distance

C、room

D、gap


参考答案：D

第4题：

共用题干
The Impact of Antarctic Ozone Hole

The Antarctic ozone（臭氧）hole is changing weather patterns across the Southern Hemisphere （半球）,even affecting the tropics,scientists have concluded. The scientists______(51)the new study added the ozone hole into standard climate models to_______(52)how it might have affected winds and rains. They say rainfall has moved further south towards the pole and the effect has been_______(53)strong over Australia.
And of_______(54)interest was the southward of the Southern Hemisphere jet stream. These high一altitude winds are_______(55)to determining weather patterns,in both hemispheres. Much of the cold weather felt in the UK_______(56)the last couple of winters,for example,was caused by blocking of the Northern Hemisphere stream.
The team found that overall,the ozone hole has_______(57)in rainfall moving south along with the winds._______(58)there are regional differences,particularly concerning Australia. In terms of the average for that zone,the ozone hole_______(59)about a 10% change一but for Australia,it's about 35%.
Their modeling indicated that global warming_______(60)greenhouse gas emissions is also a factor in changing rainfall patterns.
Natural climate cycles are also thought to be important here,as different rainfall patterns were _______(61)in the era before ozone depletion（消耗）and late 20th Century warming.
Although the_______(62)international organization has significantly checked emissions of harmful substances,they_______(63)for decades in the atmosphere,and so their effects are still being felt.Earlier,and international organization forecast that even the Antarctic ozone hole一which is more severe than its_______(64)in the Northern Hemisphere一should be_______(65)by 2045—2060.

_________(54)
A:particular
B:special
C:especial
D:specific

答案：A
解析：
本题考查对上下文的理解。本空所在句中，科学家和研究应该是动宾关系，但这里又不需要一个句子的结构，而需要名词结构作本句的主语，指“从事参与研究的科学家”。因此需要一个介词，既能表达参与的意思，又能确保这个短语为名词短语。只有behind符合，behind在此处意思是“在……背后，为……负责”。因此本题的正确选项应该是B。
本题考查对上下文的理解和对动词的辫析。这句话的意思是：参与此项新研究的科学家们把臭氧层加入标准化气候模型，以研究其如何影响风和雨的格局。本空前是to，后是how，根据上下文可以推断，这里是用不定式表达科学家所做的事情的目的，所以正确答案是选项C investigate调查。其他选项的意思分别是：选项A inspect监视；选项B scan扫描；选项D supervise监管。
本题考查对上下文的理解和对副词的辨析。这句话的意思是：科学家称降雨已向南极进一步移动，对澳大利亚的影响尤为强烈。这篇文章主要是关于南极臭氧层空洞的影响，作者提到具体影响的地点就应该是强调其影响之大，所以正确答案是选项A remarkably非常地。其他选项的意思分别是：选项B preferably更可取地、更好地；选项C indispensably不可缺少地、绝对必要地；选项D plausibly似真地。
本题考查对上下文的理解和介词短语固定搭配。这句话的意思是：科学家们尤为感兴趣的是南半球急流的南移。选A的依据是第一段最后一句：科学家称降雨已向南极进一步移动，所以第二段第一句所讲的interest应该是指科学家的兴趣，而此句后文证明本段讲的是科学家研究的更具体的内容，即南极臭氧空洞对于南半球急流的影响。空前是介词of，空后是名词interest, of particular interest的意思是尤其使人感兴趣的，符合上下文的需要，选项A particular特别的，是正确答案。其他选项的意思分别是：选项B special特别的，但不适用于of…interest这一短语；选项C especial特别的，但也不能和of以及interest组成固定搭配；选项D specific具体的。
本题考查对上下文的理解和形容词短语。这句话的意思是：这些高空风是决定南北半球气候模式的关键。选B的依据是本空的前面提到了风，后面提到了气候模式，常识告诉我们风影响甚至决定气候模式；又由于本空前是系动词are，本空后to后面跟的是动名词determining，而只有选项B key关键，能和前后词构成符合上下文需要的短语be key to是……的关键。所以选项B是正确答案。其他选项与to搭配后的意思分别是：选项A be beneficial to对……有益；选项C be necessary to对……而言必要；选项D be vital to对……至关重要。而这三个形容词后面的to都是不定式标志，其后要跟动词原形。
本题考查对上下文的理解和介词辫析。空后提到：the last couple of winters过去的几个冬天，是表示时间的名词短语。四个选项中，只有选项C能表示在……期间，所以选项C是正确答案。其他选项的意思分别是：选项A around大约（在）；选项B along沿着；选项D across横跨。这三个选项不和时间连用，或者不强调时间跨度，不符合上下文需要。
本题考查对上下文的理解和动词辫析。这句话的意思是：这个研究团队发现，臭氧层空洞总体上导致了降雨随风向南移动。文章主题是臭氧层空洞会改变气候，而 rainfall属于气候范畴，由此可判断此处具体讲臭氧层空洞对降雨的影响。result in导致，符合上下文要求，所以选项A resulted是正确答案。其他选项与in搭配的动词原形意思分别是：选项B draw in到达、变短；选项C bring in产生；选项D drop in顺便拜访。
本题考查对上下文的理解和语义逻辑。这句话的意思是：但是存在着地区差异，尤其在澳大利亚上空。上一句讲整体上的（overall）情况而本句说到“有地区差异 ( regional differences)"，两句为转折关系，选项B But的意思是但是，所以选项B是正确答案。
本题考查对上下文的理解和动词辫析。该句是上一句的例证，上一句说臭氧层空洞对降雨的影响有地区差异，所以此处是要表示“影响”的词，符合的只有选项A drive change推动变化，且文章主题（臭氧层空洞会改变气候模式）也是提示。所以选项A是正确答案。选项B attract吸引；选项C motivate激发、诱发；选项D include包括。
本题考查对上下文的理解和介词短语辫析。这句话的意思是：他们的模型表明，由温室气体排放所导致的全球变暖也是改变降雨格局的一个因素。greenhouse gas emissions"温室气体排放”是导致global warming“全球变暖”的原因，选项A due to的意思是由于，所以A是正确答案。其他选项的意思是：选项B along with和……一道；选项C as for至于；选项D instead of而不是。
本题考查对上下文的理解。这句话的意思是：自然气候周期也是一个很重要的因素，因为在臭氧消耗和20世纪末期全球变暖之前就发现有不同的降雨格局。选B的依据是：此处是被动句，表示“不同的降雨格局在……之前已经被‘留意到、观察到”,，因此选项B noted符合文意。此处为过去的客观事实，因此选项A predicted“预言、预测”不符合；选项 C occured“发生、出现、存在”语义符合，但它一般直接用主动语态；选项D descend“下降、下来”不符合题意。所以选项B是正确答案。
本题考查对上下文的理解和形容词辫析。这句话的意思是：虽然相关国际组织已经明显控制了有害气体的排放量，但这些有害气体还会在大气中留存几十年，因此它们的影响仍然存在。此处需修饰international organization的词，只有选项D corresponding相应的，符合题意，表示“相应的国际组织”。所以选项D是正确答案。其他选项的意思是：选项A popular流行的；选项B controversial有争议的；选项C distinctive独特的。
本题考查对上下文的理解和动词辫析。选D的依据是：本空后的so表明该句是下句的原因，下句说有害气体的影响还存在，由此可推断这些物质几十年来还留存在大气中，所以选项D endure是正确答案。其他选项的意思分别是：选项A flash闪烁；选项B fluctuate波动；选项C suffer遭受、遭殃。
本题考查对上下文的理解和名词辫析。本句的意思是：早前，一个国际机构预测：比北极臭氧层空洞更严重的南极臭氧层空洞将在2045年到2060年得到修复。more than说明是比较，此处把Antarctic ozone hole与在Northern Hemisphere的同类事物作比较，南北极的臭氧空洞属于对等物，所以选项C equivalent对等物、相等物是正确答案。其他选项的意思分别是：选项A illusion幻觉、错觉；选项B image形象；选项D extension延长部分。
本题考查对上下文的理解和动词辫析。选择D的依据是：此空所填动词的宾语是the Antarctic ozone hole“南极臭氧层空洞”，可以接此宾语的只有选项D repaired修复。选项A repeated重复；选项B reproduced繁殖、复制；选项C replaced代替。

第5题：

共用题干
Sunbath and Skin Cancer
In the summer,millions of Americans will offer up their bodies to the sun rays.A tan mndi-cates health and beauty,and most sun worshippers will sacrifice a lot to achieve it,including themselves.
With each hour, the sun's ultraviolet radiation (紫外线）produces irreversible（不可逆的） damage,hastening the development of unsightly wrinkles.And with each year on the beach or roof-top,the sunbather increases his risk of getting skin cancer. Skin cancer is by far the most common form of cancer. An estimated 400,000 new cases will be detected this year in the United States, and almost all of them can be blamed on over-exposure to the sun.
Fortunately,most of these cancers are highly curable .But they can he disfiguring and take time to treat. For that reason,sun worshippers should treat deity with a good deal of awe（敬畏）. Sunburn,of course,is the initial hazard posed by UV radiation.Prolonged exposure to UV,howev-er , interferes with the production of collagen fibers（胶原纤维）in the dermis（真皮层）, causing the skin to lose elasticity（弹性）and creating premature wrinkles. Further deterioration（恶化）of the dermis deprives the epidermis（表皮层）of nutrition and causes it to become thin and dry.
Cancer is UV's final result.Shortwave radiant energy,especially from the UV-B band,breaks the strands（股、缕）of DNA. Enzymes（酶）work constantly to rearrange the DNA into proper Se-quence,but with repeated UV exposure,the repair process may eventually break down.Then the mutant（变异的）DNA may produce a colony of cancer cells. But skin cancer may be avoided with a good dose of common sense.People with fair skin and blue eyes who burn easily stand the high-est risk .Special danger spots are the parts of the body most constantly exposed to the sun,such as the cheeks , nose , lower lip and the ears. People who have already developed precancerous（癌变前的）lesions（伤害）or had one skin-cancer growth stand a greatly increased chance of developing others.
Dermatologists（皮肤科医生）recommend avoiding the sun when it is most intense between 11 a.m.and 3 p.m.Anyone who insists on sunbathing should use a good sun screen.These lotions and salves（药膏）contain chemicals that block out the burning UVB radiation while permitting the tanning rays to reach the skin.

The last paragraph of the passage mainly discusses_______.
A: the treatment of the skin cancer
B: the prevention of the skin cancer
C: the parts of the body where cancer is most likely to develop
D: the lotions that work best in fighting against the skin cancer

答案：B
解析：
在读题时应抓住“over-exposure”一词，在第二段的最后一句“… and almost all of them can be blamed on over-exposure to the sun. ” A项“皱纹”和D项“健康美”都是一般的暴硒引起的而非过度暴硒引起。C项“不惜一切代价”跟过度暴硒没有因果关系。


由第三段可知，皮肤癌即使被治愈，但患者的容貌有可能受损，而导致皮肤癌的正是太阳光，因此可以推断人们应该躲避的是阳光（太阳），而不是皮肤癌。同时，原文是“ treat deity with a good deal of awe（敬畏）”一般是时待神灵才是“满怀敬畏”，而西方传说中太阳也是一位神灵，即太阳神。综上所述，可以推断本题选C。


在文章第三段的第四句“Sunburn , of course , is the initial hazard posed by UV radia-tion.”皮肤变黑实际上是红外线辐射对人体产生的最初危害。先是硒黑，接下来才是真皮受损、失去弹性，损伤表皮。


答案在第四段的第三、第四句“Enzymes(酶) work constantly to rearrange the DNA into proper sequence,but with repeated UV exposure,the repair process may eventually break down. Then the mutant（变异的）DNA may produce a colony of cancer cells.”长时间的暴硒造成修复过程崩溃，并有可能导致癌细胞产生。


其实只要抓住“Dematologists（皮肤科医生）recommend”“avoiding the sun”“ sun screen”“block out”等关键词就能理解最后一段讨论如何预防皮肤癌。

第6题：

In the Northern Hemisphere, when the center of a high pressure system is due east of your position, you can expect winds from the ______.

A.south to east

B.north to west

C.north to east

D.south to west


正确答案：A
在北半球，如果高压中心在你的东部，你预料到是什么风向？东南风。

第7题：

共用题干
Sunbath and Skin Cancer
In the summer,millions of Americans will offer up their bodies to the sun rays.A tan mndi-cates health and beauty,and most sun worshippers will sacrifice a lot to achieve it,including themselves.
With each hour, the sun's ultraviolet radiation (紫外线）produces irreversible（不可逆的） damage,hastening the development of unsightly wrinkles.And with each year on the beach or roof-top,the sunbather increases his risk of getting skin cancer. Skin cancer is by far the most common form of cancer. An estimated 400,000 new cases will be detected this year in the United States, and almost all of them can be blamed on over-exposure to the sun.
Fortunately,most of these cancers are highly curable .But they can he disfiguring and take time to treat. For that reason,sun worshippers should treat deity with a good deal of awe（敬畏）. Sunburn,of course,is the initial hazard posed by UV radiation.Prolonged exposure to UV,howev-er , interferes with the production of collagen fibers（胶原纤维）in the dermis（真皮层）, causing the skin to lose elasticity（弹性）and creating premature wrinkles. Further deterioration（恶化）of the dermis deprives the epidermis（表皮层）of nutrition and causes it to become thin and dry.
Cancer is UV's final result.Shortwave radiant energy,especially from the UV-B band,breaks the strands（股、缕）of DNA. Enzymes（酶）work constantly to rearrange the DNA into proper Se-quence,but with repeated UV exposure,the repair process may eventually break down.Then the mutant（变异的）DNA may produce a colony of cancer cells. But skin cancer may be avoided with a good dose of common sense.People with fair skin and blue eyes who burn easily stand the high-est risk .Special danger spots are the parts of the body most constantly exposed to the sun,such as the cheeks , nose , lower lip and the ears. People who have already developed precancerous（癌变前的）lesions（伤害）or had one skin-cancer growth stand a greatly increased chance of developing others.
Dermatologists（皮肤科医生）recommend avoiding the sun when it is most intense between 11 a.m.and 3 p.m.Anyone who insists on sunbathing should use a good sun screen.These lotions and salves（药膏）contain chemicals that block out the burning UVB radiation while permitting the tanning rays to reach the skin.

Which of the following comes first as a possible damage by UV radiation?
A: Sunburn.
B: The loss of skin elasticity.
C: Dryness of epidermis.
D: The deterioration of dermis.

答案：A
解析：
在读题时应抓住“over-exposure”一词，在第二段的最后一句“… and almost all of them can be blamed on over-exposure to the sun. ” A项“皱纹”和D项“健康美”都是一般的暴硒引起的而非过度暴硒引起。C项“不惜一切代价”跟过度暴硒没有因果关系。


由第三段可知，皮肤癌即使被治愈，但患者的容貌有可能受损，而导致皮肤癌的正是太阳光，因此可以推断人们应该躲避的是阳光（太阳），而不是皮肤癌。同时，原文是“ treat deity with a good deal of awe（敬畏）”一般是时待神灵才是“满怀敬畏”，而西方传说中太阳也是一位神灵，即太阳神。综上所述，可以推断本题选C。


在文章第三段的第四句“Sunburn , of course , is the initial hazard posed by UV radia-tion.”皮肤变黑实际上是红外线辐射对人体产生的最初危害。先是硒黑，接下来才是真皮受损、失去弹性，损伤表皮。


答案在第四段的第三、第四句“Enzymes(酶) work constantly to rearrange the DNA into proper sequence,but with repeated UV exposure,the repair process may eventually break down. Then the mutant（变异的）DNA may produce a colony of cancer cells.”长时间的暴硒造成修复过程崩溃，并有可能导致癌细胞产生。


其实只要抓住“Dematologists（皮肤科医生）recommend”“avoiding the sun”“ sun screen”“block out”等关键词就能理解最后一段讨论如何预防皮肤癌。

第8题：

翻译句子The South Pole, by contrast, is over land, on the continent called Antarctica. Not only is the South Pole on a continent, it's on a very high continent.


参考答案：相反，南极点位于我们称为南极洲的陆地之上。南极点不仅位于大陆之上，而且是在一个很高的大陆之上。

第9题：

共用题干
Sunbath and Skin Cancer
In the summer,millions of Americans will offer up their bodies to the sun rays.A tan mndi-cates health and beauty,and most sun worshippers will sacrifice a lot to achieve it,including themselves.
With each hour, the sun's ultraviolet radiation (紫外线）produces irreversible（不可逆的） damage,hastening the development of unsightly wrinkles.And with each year on the beach or roof-top,the sunbather increases his risk of getting skin cancer. Skin cancer is by far the most common form of cancer. An estimated 400,000 new cases will be detected this year in the United States, and almost all of them can be blamed on over-exposure to the sun.
Fortunately,most of these cancers are highly curable .But they can he disfiguring and take time to treat. For that reason,sun worshippers should treat deity with a good deal of awe（敬畏）. Sunburn,of course,is the initial hazard posed by UV radiation.Prolonged exposure to UV,howev-er , interferes with the production of collagen fibers（胶原纤维）in the dermis（真皮层）, causing the skin to lose elasticity（弹性）and creating premature wrinkles. Further deterioration（恶化）of the dermis deprives the epidermis（表皮层）of nutrition and causes it to become thin and dry.
Cancer is UV's final result.Shortwave radiant energy,especially from the UV-B band,breaks the strands（股、缕）of DNA. Enzymes（酶）work constantly to rearrange the DNA into proper Se-quence,but with repeated UV exposure,the repair process may eventually break down.Then the mutant（变异的）DNA may produce a colony of cancer cells. But skin cancer may be avoided with a good dose of common sense.People with fair skin and blue eyes who burn easily stand the high-est risk .Special danger spots are the parts of the body most constantly exposed to the sun,such as the cheeks , nose , lower lip and the ears. People who have already developed precancerous（癌变前的）lesions（伤害）or had one skin-cancer growth stand a greatly increased chance of developing others.
Dermatologists（皮肤科医生）recommend avoiding the sun when it is most intense between 11 a.m.and 3 p.m.Anyone who insists on sunbathing should use a good sun screen.These lotions and salves（药膏）contain chemicals that block out the burning UVB radiation while permitting the tanning rays to reach the skin.

What may be the worst result after the repair process of the DNA finally fail?
A:Shortwave radiant energy breaks the strands of the DNA.
B:The mutant DNA may produce a colony of cancer cells.
C: Enzymes work to rearrange the DNA into a new order.
D:The patient is exposed to UV from time to time.

答案：B
解析：
在读题时应抓住“over-exposure”一词，在第二段的最后一句“… and almost all of them can be blamed on over-exposure to the sun. ” A项“皱纹”和D项“健康美”都是一般的暴硒引起的而非过度暴硒引起。C项“不惜一切代价”跟过度暴硒没有因果关系。


由第三段可知，皮肤癌即使被治愈，但患者的容貌有可能受损，而导致皮肤癌的正是太阳光，因此可以推断人们应该躲避的是阳光（太阳），而不是皮肤癌。同时，原文是“ treat deity with a good deal of awe（敬畏）”一般是时待神灵才是“满怀敬畏”，而西方传说中太阳也是一位神灵，即太阳神。综上所述，可以推断本题选C。


在文章第三段的第四句“Sunburn , of course , is the initial hazard posed by UV radia-tion.”皮肤变黑实际上是红外线辐射对人体产生的最初危害。先是硒黑，接下来才是真皮受损、失去弹性，损伤表皮。


答案在第四段的第三、第四句“Enzymes(酶) work constantly to rearrange the DNA into proper sequence,but with repeated UV exposure,the repair process may eventually break down. Then the mutant（变异的）DNA may produce a colony of cancer cells.”长时间的暴硒造成修复过程崩溃，并有可能导致癌细胞产生。


其实只要抓住“Dematologists（皮肤科医生）recommend”“avoiding the sun”“ sun screen”“block out”等关键词就能理解最后一段讨论如何预防皮肤癌。

第10题：

共用题干
第一篇
The Northern Lights
The sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.
The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.
Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.
Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.
We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!

What is the author's tone toward the Northern Lights?
A:Indifferent.
B:Sarcastic.
C:Sharp.
D:Appreciative.

答案：D
解析：
本篇文章主要介绍了北极光的形成、运动以及色彩。
根据第一段第三、四句可知，热量在时速约100万英里的带电粒子流中由太阳向地球流动，这些粒子被称为等离子体，源于太阳的等离子体流又被称为太阳风。由此不难推测出，太阳风是能量从太阳向地球高速流动造成的，所以选择C项。
根据第二段第三句可知，带电粒子被困在环绕地球的磁场中，并且根据第一段第三、四句以及第二段第一句可知，这些带电粒子即为太阳风。由此可知，太阳风吹向地球时，会被地球外围的磁场束缚住，所以选择A项。
根据第二段最后一句可知，电子落向地球时与大气中的气体分子碰撞而产生了光芒；根据第三段第一句和第三句可知，碰撞后每种大气分子发出的光芒不同；不同的光芒在天空中闪现，造成了北极光和南极光；根据第二段第五句可知，原子粒子被称为电子。由此推出，北极光是由电子，即原子粒子，与大气中的气体分子碰撞造成的。
根据第四段第二句可知，北极光穿过天空的速度通常足够慢，能够让人看到，但是它们可能也会跳动、闪烁，甚至会像波浪一样。由此可知，北极光移动的速度很慢，能够被人用眼观察，所以选择A项。
最后一段表明，作者希望望人在一生中至少应该去看一次北极光，并且说他知道我们会感到难忘。可见作者对北极光是喜爱的，所以选择D项。

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