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 |
Dorothea Shaw is 71 years old and nearly blind, and she chose to live alone far away from people. She lives in Belize — a county the size of Wales with a population only that of Swansea. Her home is at Gales Point, a tiny village which can be reached only by sea or air; after a 10-mile walk into the hills one finally reaches a piece of land and two small houses so hidden in the thick over-grown forest that only a handful of people know Dorothea is there.
She lives happily and totally alone – growing her vegetables, looking after her trees and dogs, cats and chickens. Once a month or so an old friend passes by with her food supplies and letters-usually including a letter from her sister in Scunthorpe and some bits of clothing from friends in Canada. Sometimes a local man will come and cut wood for her and a group of British soldiers will come across her and be greeted with the offer of a cup of coffee.
At night she lies in her tiny sleeping room with the dogs on the floor, the cats on the table near the typewriter and one of the hens settled down in a corner of the bookshelf, and listens for hours to any Spanish, English, German or French broadcasts she can find on her radio. Sometimes she gets lonely but most of the time the animals and the radio are company enough.
But recently the very things that she had tried to get free from so well have begun to catch up with her. The peace of the forest has been destroyed by the noise of earth-moving machines not many miles away. What she once only heard of distantly on the radio is now on her doorstep. Things began to change three years ago. The new main north-south road in Belize was cut through the forest only four or five miles away. “Now more people know I’m here.” She says. “I feel more and more uneasy each day.”Dorothea’s small houses ________.
| A．are entirely surrounded by trees |
| B．have always been her home |
| C．were built for just a few people |
| D．are in a county with the same population as Wales |
Dorothea lives in the tiny village because ________.
| A．she doesn’t like living near people | B．she is too old to move |
| C．machines destroyed her home | D．there’s nowhere else for her to live |
Dorothea doesn’t get lonely since she has _______ with her.
| A．her sister | B．some animals | C．friends from Canada | D．a postman |
Dorothea spends a lot of time __________.
| A．growing all the food she needs | B．cutting down trees |
| C．listening to the radio | D．studying languages |
Millions of people visit Yosemite National Park every year to see the tall waterfalls and mountains. The mountains are a splendid sight when viewed from the valley floor. Lots of stores, hotels, and restaurants are needed to handle the crowds. Also, water, roads, and other service systems are part of the infrastructure(基础设施)that must be maintained.
Unfortunately, these systems are starting to break down. It’s not just in Yosemite but in national parks around the nation.
Yosemite is thirty years old according to Dennis Galvin, a National Park Service worker. The park is not only old but worn out. Two or three times as many visitors come every year. That is too many visitors for the park to deal with.
Four years ago a storm washed out a water pipeline in the Grand Canyon. The National Park service had to send water trucks to provide water for the visitors. Last month pipes almost broke again and roads had to be closed for a while.
Why hasn’t the National Park Service kept up the park repairs? There is a lack of money. The United States has 378 monuments, parks, and wilderness areas. Between three and four billion dollars are needed for repairs.
Yosemite is one national park that does have money for repairs. It has two hundred million dollars but cannot spend it any way it chooses. When the park workers started widening the road, they were forced to stop by the Sierra Club. The club claimed that the road work was damaging the Merced River that runs through the park.
A Sierra Club lawyer, Julia Olson, feels that the infrastructure needs to be moved out of Yosemite. That way less pressure will be put on the already crowded park.According to the text, the mountains in Yosemite look most splendid when they are appreciated from _______.
| A．the bottom of the valleys | B．the top of the mountains |
| C．the side of the mountains | D．the edge of the valleys |
National parks like Yosemite in the U.S. find it increasingly difficult to meet the need of visitors because ________.
| A．the transport management needs improving |
| B．they spend too much on their service systems |
| C．their service systems frequently go out of order |
| D．they need help from environmental organizations |
The main problem of Yosemite National Park is its _______.
| A．rundown water pipes | B．overcrowdedness | C．lack of money | D．narrow roads |
According to the text, the Sierra Club is most likely to be ______.
| A．an environmental group | B．an information center |
| C．a travel service | D．a law firm |
People express their personalities in their clothes, their cars, and their homes. Our diets can also show our personalities because we might choose certain food to tell people something about us.
For example, some people mainly enjoy high quality food, such as caviar (鱼子酱) and lobster (龙虾), and they eat only in expensive restaurants – never in cafeterias or bars. They know about the “better things in life”.
Some people choose not to eat meat. Vegetarians often have more in common than just their diet. Their personalities might be similar too. For instance, vegetarians in the United States and Canada may be creative people, and they might not enjoy competitive sports or jobs. They worry about the health of the world, and they are probably strongly against the war.
Some people eat mostly fast food. One study shows that many fast-food eaters have a lot in common, but they are very different from vegetarians. They are competitive and good at business. They are also usually in a hurry. Many fast-food eaters might not agree with this description of their personalities, but it is a common picture of them.
Some people also believe that people of the same astrological sign（星座）have similar food personalities. Aries (born under the sign of Aries, between March 21 and April 20) usually like spicy foods, with a lot of onions and pepper. People with the sign of Taurus (April 21 to May 22) prefer healthful fruits and vegetables, but they often eat too much. Sagittarius (November 22 to December.22) like traditional food from many different countries.
What is your food personality?Why do some people mainly eat high quality food?
| A．They want to show off their wealth. | B．Food can show off their social position. |
| C．They want to enjoy better things in life. | D．They are wiser than any other persons. |
A vegetarian may be a person________.
| A．who is believed to be a peace – lover | B．who values the importance of success |
| C．who cares little about the future of the world | D．who shows his power to make money |
From the passage, we can draw a conclusion that_____________.
| A．food is just a mirror of the human history |
| B．we can know a person from what he eats |
| C．people are particular about the food they eat |
| D．what people eat may change their personalities |
Dear Cassy,
Thanks for reminding me by e-mail that you want to baby-sit our children. Although you are only 12 years old, my wife and I would be willing to consider your application（申请）if you can meet(满足) a few requirements:
1）Send us three letters from teachers who will prove that you have never failed to follow instructions perfectly in class and never failed to hand in your homework on time.
2）Send us a note from two doctors who will prove that you are in perfect health, have never been sick, and never will be sick.
3）Send us a document from your physical education teacher or team coach that proves that you can do each of the following: Run two miles in less than four minutes, climb an oiled rope to a height of twenty feet in thirty seconds while balancing a glass of water on your nose, and walk in bare feet over hot coals and broken glass without injury.
4）Send us notarized（得到公证的）letters from at least two mental health experts saying that you have never had an envious thought towards other people.
5）Play and defeat five expert chess players while blindfolded（蒙着眼睛）after going without sleep for 48 hours.
6)Wait patiently（耐心地）for two years while we have investigators（调查）certify（确保）that all your documents（文件）are real.
Your loving and trusting friends,
The SmithsThe Smiths send their message to Cassy by .
| A．e-mail | B．a letter | C．a newspaper | D．a report |
According to the first paragraph,.
| A．the Smiths must have had an advertisement made, saying that they want someone to look after their children |
| B．the Smiths have informed Cassy that they need some children |
| C．the Smiths have promised to provide what Cassy asked for |
| D．the Smiths would be very glad if Cassy can meet their requirements |
What is the attitude of the Smiths about hiring the 12-year old girl to look after their baby?
| A．The Smiths try to tell her how to baby-sit children. |
| B．The Smiths don’t think a girl is good for the job. |
| C．The Smiths don’t want to hire her. |
| D．The Smiths are willing to offer her the job. |
Which of the requirements mentioned by the Smiths do you think Cassy can meet?
| A．All of them | B．Half of them |
| C．None of them | D．Most of them |
Our 16-year-old daughter started to smoke last Christmas. It killed me to see that lovely girl with a cigarette(香烟) in her mouth. I told her how I felt. Martha continued to smoke, saying, “It's my life,” and so on. I told her if she didn't stop smoking, I wouldn't send her to college. She agreed to give it up.
Last night there was cigarette smell on Martha's breath. She had to say she had broken her word. Now I must do what I've said to punish(惩罚) her.
Martha is unusually bright and wants to teach children. I'm working full-time to put her older sister through school and would do the same for Martha. My husband's pay is good, but with prices going up all the time we could never educate the girls unless I kept on working.
My theory(理论) is that if smoking is more important to Martha than college, I'm a fool to work to put her through college.Why did the mother feel sad?
| A．Because her daughter failed to go to college. |
| B．Because her daughter tried to kill her. |
| C．Because her daughter promised to smoke no more. |
| D．Because her daughter got used to smoking. |
The mother warned that if Martha didn't give up smoking, she would ______.
| A．refuse to give Martha any money |
| B．not be Martha's mother |
| C．refuse to pay for Martha's college education |
| D．not let Martha teach children |
What did Martha really do after mother warned her?
| A．She failed to keep her promise. |
| B．She kept her promise. |
| C．She managed to give up smoking. |
| D．She broke something her mother gave her. |
The mother said that ______.
| A．Martha was usually a stupid girl |
| B．though Martha's father received high pay, it was not enough for their two girls' college education |
| C．as everything was becoming more and more expensive, the two girls had to work hard to pay for their education |
| D．she liked Martha's sister but hated Martha |