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Some people fear that ________ air pollution may bring about changes in _______ weather around the world. 21世纪教育网

A. /; the　　　 B. the; /　　　 C. an; the　　　 D. the; a 21世纪教育网

 

【答案】A

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Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour.

The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

Scientists have changed the colour of a dark-striped zebrafish to uniform gold by inserting a version of the pigment(色素) gene into a young fish. As with humans, zebrafish skin colour is determined by pigment cells, which contain melanosomes(黑色素). The number, size and darkness of melanosomes per pigment cell determines skin colour.

It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation(变异) in the gene for melanosome production. This results in less pigmented skin.

However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebrafish genes.

Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun(太阳光紫外线), which can cause skin cancer.

But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin colour, said Cheng.

The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment did on Michael Jackson.

The passage mainly tells us that ________.

  A. people can not change their skin colour without any pain

  B. the new discovery could lead to search into ways to change skin colour safely

  C. pop king Michael Jackson often changed his skin colour as he liked

  D. scientists have found out that people’s skin colour is determined by the gene

It can be inferred from the passage that ________.

  A. nowadays people who want to change their skin colour have to suffer a lot from the damage caused by the chemical  treatment

  B. Europeans and Africans have the same gene

  C. the new discovery could help to find medical treatments for skin cancer

  D. there are two kinds of genes

Scientists have done an experiment on a dark-striped zebra fish in order to ________.

  A. find the different genes of humans’

  B. prove the humans’ skin colour is determined by the pigment gene

  C. find out the reason why the Africans’ skin colour is dark

  D. find out the ways of changing peopl’s skin colour

The writer’s attitude towards the discovery is ________.

  A. neutral                      B. negative                   C. positive                    D. indifferent

Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour.

The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

Scientists have changed the colour of a dark-striped zebrafish to uniform gold by inserting a version of the pigment(色素) gene into a young fish. As with humans, zebrafish skin colour is determined by pigment cells, which contain melanosomes(黑色素). The number, size and darkness of melanosomes per pigment cell determines skin colour.

It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation(变异) in the gene for melanosome production. This results in less pigmented skin.

However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebrafish genes.

Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun(太阳光紫外线), which can cause skin cancer.But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin colour, said Cheng.

The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment did on Michael Jackson.

The passage mainly tells us that ________.

  A. people can not change their skin colour without any pain

  B. the new discovery could lead to search into ways to change skin colour safely

  C. pop king Michael Jackson often changed his skin colour as he liked

  D. scientists have found out that people’s skin colour is determined by the gene

It can be inferred from the passage that ________.

  A. nowadays people who want to change their skin colour have to suffer a lot from the damage caused by the chemical  treatment                                 B. Europeans and Africans have the same gene

  C. the new discovery could help to find medical treatments for skin cancer    D. there are two kinds of genes

Scientists have done an experiment on a dark-striped zebra fish in order to ________.

  A. find the different genes of humans’

  B. prove the humans’ skin colour is determined by the pigment gene

  C. find out the reason why the Africans’ skin colour is dark  D. find out the ways of changing peopl’s skin colour

The reason why Europeans are light-skinned is probably that ________.

  A. they are born light-skinned people

  B. light-skinned Europeans have mutation in the gen for melanosome production

  C. they have fewer activities outside          D. they pay much attention to protecting their skin

The writer’s attitude towards the discovery is ________.

  A. neutral                      B. negative                   C. positive                    D. indifferent

Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour.

The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

Scientists have changed the colour of a dark-striped zebrafish to uniform gold by inserting a version of the pigment(色素) gene into a young fish. As with humans, zebrafish skin colour is determined by pigment cells, which contain melanosomes(黑色素). The number, size and darkness of melanosomes per pigment cell determines skin colour.

It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation(变异) in the gene for melanosome production. This results in less pigmented skin.

However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebrafish genes.

Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun(太阳光紫外线), which can cause skin cancer.

But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin colour, said Cheng.

The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment did on Michael Jackson.

51. The passage mainly tells us that ________.

  A. people can not change their skin colour without any pain

  B. the new discovery could lead to search into ways to change skin colour safely

  C. pop king Michael Jackson often changed his skin colour as he liked

  D. scientists have found out that people’s skin colour is determined by the gene

52. It can be inferred from the passage that ________.

  A. nowadays people who want to change their skin colour have to suffer a lot from the damage caused by the chemical  treatment

  B. Europeans and Africans have the same gene

  C. the new discovery could help to find medical treatments for skin cancer

  D. there are two kinds of genes

53. Scientists have done an experiment on a dark-striped zebra fish in order to ________.

  A. find the different genes of humans’

  B. prove the humans’ skin colour is determined by the pigment gene

  C. find out the reason why the Africans’ skin colour is dark

  D. find out the ways of changing peopl’s skin colour

54. The reason why Europeans are light-skinned is probably that ________.

  A. they are born light-skinned people

  B. light-skinned Europeans have mutation in the gen for melanosome production

  C. they have fewer activities outside

  D. they pay much attention to protecting their skin

55. The writer’s attitude towards the discovery is ________.

  A. neutral                      B. negative                   C. positive                    D. indifferent

Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour.

The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

Scientists have changed the colour of a dark-striped zebrafish to uniform gold by inserting a version of  the pigment(色素) gene into a young fish. As with humans, zebrafish skin colour is determined by pigment cells, which contain melanosomes(黑色素). The number, size and darkness of melanosomes per pigment cell determines skin colour.

It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation(变异) in the gene for melanosome production. This results in less pigmented skin.

However, Keith Cheng, leader of the research team, points out that the mutation is dif ferent in human and zebrafish genes.

Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun(太阳光紫外线), which can cause skin cancer.

But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vit amin D. So the related gene changes, according to Cheng.

Asians have the same version of the gene as Africans, so they pr obably acquired their light skin through the action of some other gene that affects skin colour, said Cheng.

The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment did on Michael Jackson.

 

1.. The passage mainly tells us that ________.

  A. people can not change their skin colour without any pain

  B. the new discovery could lead to search into ways to change skin colour safely

  C. pop king Michael Jackson often changed his skin colour as he liked

  D. scientists have found out that people’s skin colour is determined by the gene

2.. Scientists have done an experiment on  a dark-striped zebra fish in order to ________.

  A. find the  different genes of humans’

  B. prove the humans’ skin colour is determined by the pigment gene

  C. find out the reason why the Africans’ skin colour is dark

  D. find out the ways of changing peopl’s skin colour

3.. The reason why Europeans are light-skinned is probably that ________.

  A. they are born light-skinned people

  B. light-skinned Europeans have mutation in the gene for melanosome production

  C. they have fewer activities outside

  D. they pay much attention to protecting their skin

 
阅读理解
     That cold January night, I was growing sick of my life in San Francisco. There I was walking home 
at one in the morning after a tiring practice at the theater. With opening night only a week away, I was 
still learning my lines. I was having trouble dealing with my part-time job at the bank and my acting at 
night at the same time. 
     As I walked, I thought seriously about giving up both acting and San Francisco. City life had become 
too much for me. As I walked down empty streets under tall buildings, I felt very small and cold. I began 
running, both to keep warm and to keep away from any possible robbers. Very few people were still 
out except a few sad-looking homeless peopl e under blankets.
     About a block from my apartment, I heard a sound behind me. I turned quickly, half expecting to 
see someone with a knife or a gun. The street was empty. All I saw was a shining streetlight. Still, the 
noise had made me nervous, so I started to run faster. Not until I reached my apartment building and 
unlocked the door did I realize what the noise had been. It had been my wallet falling to the sidewalk.
     Suddenly I wasn't cold or tired any more. I ran out of the door and back to where I'd heard the 
noise. Although I searched the sidewalk anxiously for fifteen minutes, my wallet was nowhere to be found.
     Just as I was about to give up the search, I heard the garbage truck pull up to the sidewalk next to 
me. When a voice called from the inside , "Alisa Camacho?" I thought I was dreaming. How could this 
man know my name? The door opened, and out jumped a small red-haired man with an amused look 
in his eyes. "Is this what you're looking for?" he asked, holding up a small square shape.
     It was nearly 3 a.m. by the time I got into bed. I wouldn't get much sleep that night, but I had got my 
wallet back. I also had got back some enjoyment of city life. I realized that the city couldn't be a bad 
place as long as people were willing to help each other.
1.How did the writer feel when she was walking home after work?
A. Cold and sick                    
B. Lucky and hopeful
C. Satisfied and cheerful              
D. Disappointed and helpless
2.From the first paragraph, we learn that the writer was busy _____.
A. solving her problem at the bank      
B. getting used to the city life
C. learning acting in an evening school   
D. preparing for the first night show
3.On her way home the writer______.          
A. lost her wallet unknowingly
B. talked a lot with a garbage truck driver
C. was robbed of her wallet by a man with a knife  
D. found some homeless people following her
4.From the text, we can infer that the writer_____.
A. would stop working at night        
B. would stay on in San Francisco
C. would make friends with cleaners.   
D. would give up her job at the bank

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