Batteries can power anything from small sensors to large systems. While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves. University of Missouri(MU) researchers are developing a nuclear energy source that is smaller, lighter and more efficient.
“To provide enough power, we need certain methods with high energy density(密度)”，said Jae Kwon, assistant professor of electrical and computer engineering at MU. “The radioisotope(放射性同位素) battery can provide power density that is much higher than chemical batteries.”
Kwon and his research team have been working on building a small nuclear battery, presently the size and thickness of a penny, intended to power various micro/nanoelectromechanreal systems (M/NEMS). Although nuclear batteries can cause concerns, Kwon said they are safe.
“People hear the word ‘nuclear’ and think of something very dangerous,” he said, “However, nuclear power sources have already been safely powering a variety of devices, such as pace-makers, space satellites and underwater systems.”
His new idea is not only in the battery’s size, but also in its semiconductor(半导体). Kwon’s battery uses a liquid semiconductor rather than a solid semiconductor.
“The key part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure(晶体结构) of the solid semiconductor,” Kwon said, “By using a liquid semiconductor, we believe we can minimize that problem.”
Together with J. David Robertson, chemistry professor and associate director of the MU Research Reactor, Kwon is working to build and test the battery. In the future, they hope to increase the battery’s power, shrink its size and try with various other materials. Kwon said that battery could be thinner than the thickness of human hair.Which of the following is true of Jae Kwon?
| A．He teaches chemistry at MU. |
| B．He developed a chemical battery. |
| C．He is working on a nuclear energy source. |
| D．He made a breakthrough in computer engineering. |
Jae Kwon gave examples in Paragraph 4_________.
| A．to show chemical batteries are widely applied. |
| B．to introduce nuclear batteries can be safely used. |
| C．to describe a nuclear-powered system. |
| D．to introduce various energy sources. |
Liquid semiconductor is used to _________.
| A．get rid of the radioactive waste | B．test the power of nuclear batteries. |
| C．decrease the size of nuclear batteries | D．reduce the damage to lattice structure. |
According to Jae Kwon, his nuclear battery _______.
| A．uses a solid semiconductor | B．will soon replace the present ones. |
| C．could be extremely thin | D．has passed the final test. |
The text is most probably a ________.
| A．science news report | B．book review |
| C．newspaper ad | D．science fiction story |
Have you ever sat on a camel? Well, if you have, then you know how scary it is when the camel rises on its long wobbly(摆动的)legs. The rocking motion of a camel is a bit like a being tossed around in heaving seas. Small wonder then that the camel is often called the ship of the desert. Actually, the name owes its origins to the fact that camels were brought from the desert, to serve as beasts of burden in other countries.
We in India are only familiar with one species of camel, known as the Dromedary camel. This animal is singlehumped, has long legs and is found in the deserts of Asia and Africa. Another specie(the twohumped shortedlegged Bactrian camel)is found in parts of China and Central Asia.
Recently, scientists discovered what they think is a new species of wild camel that lives in a remote part of China. These mammals look very similar to the Bactrian camel but they have a unique feature—they survive by drinking salty water.
Strangely enough, scientists knew about the existence of the animal, but had no idea of their unique identity(特性). As a result, researchers now admit that these animals are not Bactrian camels as initially(最初)thought, but a new species. The only visible physical difference is that the saltwater drinking species has its humps further apart than the Bactrian camel.
Camels are most common in the African and Asian deserts, but fossil evidence shows that camels originated in North America about 45 million years ago. So how did they manage to come into Africa? Well, million of years ago, North America and Asia were connected by a land mass—the presentday Bering Strait.
Scientists think that the camels migrated into South America and across to Asia, disappearing almost entirely from the land of its origin. However, many researchers say that the South American llama(骆驼)is a direct descendant of the camel.The camel is called“the ship of the desert”because________.
| A．when you are on a camel, you feel like being on a ship at sea |
| B．its long legs swung when it is traveling in the desert |
| C．camels came from the desert and are used in other countries |
| D．camels can travel in the desert of many days without eating |
What's the difference between the Dromedary camel and the Bactrian camel?
| A．The Dromedary camel has two humps. |
| B．The Bactrian camel has long legs. |
| C．The Dromedary camel is only found in Asia. |
| D．The Dromedary camel has only one hump. |
What scientists don't know about the new species is________.
| A．their existence in China |
| B．their ability to survive on salty water |
| C．their similarity to the Bactrian water |
| D．how they survive in the remote part of China |
How can people tell the new species from the the Bactrian camel?
| A．By looking at the length of their legs. |
| B．By counting the number of humps. |
| C．By looking at the distance of the two humps. |
| D．By examining the kind of the two humps. |
From the passage we can infer that________.
| A．Very few camels exist in North America at present |
| B．Camels warm across the Bering Strait to Asia |
| C．Camels first originated from the African deserts |
| D．Camels are the most endangered animals in the world |
阅读下面的短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。
E
The cost of medical care in the United States is very high. The time and money that doctors spend on their medical education is probably one reason for this problem.
A visit to a doctor's office costs from fifteen to fifty dollars. It is almost impossible for people to pay for medical care they need. Many people in the United States think that doctors are overpaid. Most doctors, however, disagree. They say that they have been required to study medicine for a long time. Tuition(学费)for many years of medical education costs lots of money. Doctors say that it is necessary for most medical students to borrow money from a bank to pay their tuition. Because this money must be repaid to the bank, young doctors need to receive a lot of money for their work. So they charge(收费)people high prices for medical care.
Therefore, it's possible that the high cost of medical care in America is unnecessary. Because high tuition is one cause of high costs, one way to lower costs would be to have medical schools that are free or have low tuition.Some people don't have their medical care they need because________.
| A．they are not willing to pay the doctors high tuition |
| B．they don't think it necessary to have medical care |
| C．they don't want to spend much money on it |
| D．they haven't got enough money to pay for it |
The reason for the high medical cost mentioned(提到)in the article is________.
| A．tuition in medical schools is high |
| B．the price of medicine is high |
| C．doctors are overpaid |
| D．doctors must pay money to banks |
One way to lower the cost of medical care would be________.
| A．not to see a doctor |
| B．to pay doctors less money |
| C．to let medical students have free or partly free medical education |
| D．to forbid(禁止)doctors to ask their patients for too much money |
The main idea of the article is that________.
| A．a visit to a doctor's office may cost as much as 15 to 50 in US |
| B．the cost of medical care is the main reason for the high costs in US |
| C．medical care in the United States costs a lot of money because doctors want to be rich |
| D．the high cost of tuition in medical schools is one reason for the high cost of medical care in America |
阅读下面的短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。
D
Parents often believe that they have a good relationship with their teenagers(青少年). But last summer, Joanna and Henry noticed a change in their older son: suddenly he seemed to be talking far more to his firends than to his parents.“The door to his room is always shut，”Joanna noted.
Tina and Mark noticed similar changes in their 14yearold daughter. “She used to cuddle up(蜷伏)with me on the sofa and talk，”said Mark. “Now we joke that she does this only when she wants something. Sometimes she wants to be treated like a little girl and sometimes like a young lady. The problem is figuring out which time is which.”
Before age 11, children like to tell their parents what's on their minds. “In fact, parents are first on the list，”said Michael Riera, author of Uncommon Sense for Parents with Teenagers. “This completely changes during the teen years，”Riera explained. “They talk to their friends first, then maybe their teachers, and their parents last.”
Parents who know what's going on in their teenagers' lives are in the best position to help them. To break down the wall of silence, parents should create chances to understand what their children want to say, and try to find ways to talk and write to them. And they must give their children a mental break, for children also need freedom, though young. Another thing parents should remember is that to be a friend, not a manager, with their children is a better way to know them.“The door to his room is always shut”suggests that the son________.
| A．is always busy with his studies |
| B．doesn't want to be disturbed |
| C．keeps himself away from his parents |
| D．begins to dislike his parents |
What troubles Tina and Mark most is that________.
| A．their daughter isn't lovely as before |
| B．they can't read their daughter's mind exactly |
| C．they don't know what to say to their daughter |
| D．their daughter talks with them only when she needs help |
Which of the following best explains“the wall of silence”in the last paragraph?
| A．Teenagers talk a lot with their friends. |
| B．Teenagers do not want to understand their parents. |
| C．Teenagers do not talk much with their parents. |
| D．Teenagers talk little about their own lives. |
What can be learned from the passage?
| A．Parents are unhappy with their growing children. |
| B．Parents have suitable ways to talk with their teenagers. |
| C．Parents should be patient with their silent teenagers. |
| D．Parents should try to understand their teenagers. |
阅读下面的短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。
C
The World Horticulture Expo(园艺博览会)to be held in Kunming, Yunnan Province, between May and October will be a good chance for visitors to discover the picturesque natural scenery of China. This year will also witness the following festivals and tours and so on.
Fragrant Hills Autumn Leaves Festival(Beijing)
International Forest Protection Festival, Zhangjiajie(Hunan)
The Three Gorges International Tourism Festival(Chongqing)
International Giant Panda Festival, Chengdu(Sichuan)
A large variety of ecotourism activities will be introduced this year all across the country.
Wild Animal Observation
Bird Watching on Bird Island in Qinghai Lake(Qinghai)
Playing with Leaf Monkeys in Longrui Nature Reserve(Guangxi)
...
Oceans & Seas
Underwater tour, diving, boating and deep sea fishing, Zhuhai(Guangdong)
Shell collecting, bathing, volleyball and kite flying on the beach and a visit to an old fishing village, ZhujiajianWhich festival will happen in Zhangjiajie this year?
| A．International Forest Protection Festival. |
| B．International Giant Panda Festival. |
| C．The Three Gorges International Tourism Festival. |
| D．Fragrant Hills Autumn Leaves Festival. |
This year you'll go to________to observe leaf monkeys.
| A．Yunnan |
| B．Henan |
| C．Sichuan |
| D．Guangxi |
If you take part in the activity, you'd better go to Zhuhai for________.
| A．sailing |
| B．bathing |
| C．diving |
| D．water skiing |
This passage is most probably________.
| A．Travel News |
| B．Travel Tips |
| C．Holiday Plans |
| D．Holiday Exhibition |
阅读下面的短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。
B
Reading to dogs is an unusual way to help children improve their literacy skills(读写能力). With their shining brown eyes, wagging tails, and unconditional love, dogs can provide the nonjudgemental listeners needed for a begining reader to gain confidence(自信心), according to Intermoutain Therapy Animals(ITA) in Salt Lake City. The group says it is the first program in the country to use dogs to help develop literacy in children, with the introduction of Reading Education Assistance Dogs(READ)．
The Salt Lake City Library is sold on the idea. “Literacy specialists admit that children who read below the level of their fellow pupils are often afraid of reading aloud in a group, often have lower selfrespect, and regard reading as a headache，”said Lisa Myron, manager of the children's department.
Last November the two groups started“Dog Day Afternoon”in the children's department of the main library. About 25 children attended each of the four Saturday—afternoon classes, reading for half an hour. Those who attended three of the four classes received a“pawgraphed”book at the last class.
The program was so successful that the library plans to repeat it in April, according to Dana Thumpowsky, public relations manager.What is mainly discussed in the text?
| A．Children's reading difficulties |
| B．Advantages of raising dogs |
| C．Service in a public library |
| D．A special reading program |
Specialists use dogs to listen to children reading because they think________.
| A．dogs are young children's best friends |
| B．children can play with dogs while reading |
| C．dogs can provide encouragement for shy children |
| D．children and dogs understand each other |
By saying“The Salt Lake City Public Library is sold on the idea”， the writer means the library________.
| A．use dogs to attract children |
| B．accepts the idea put forward by ITA |
| C．has opened a children's department |
| D．has decided to train some dogs |
A“pawgraphed”book is most probably________.
| A．a book used in Saturday classes |
| B．a book written by the children |
| C．a prize for the children |
| D．a gift from parents |