欧美日韩黄网欧美日韩日B片|二区无码视频网站|欧美AAAA小视频|久久99爱视频播放|日本久久成人免费视频|性交黄色毛片特黄色性交毛片|91久久伊人日韩插穴|国产三级A片电影网站|亚州无码成人激情视频|国产又黄又粗又猛又爽的

Why did humans evolve to walk upright? Perhaps because it’s just plain easier. Make that “energetically less costly”, scientifically speaking.
Bipedalism—walking on two feet, is one of the defining characteristics of being humans, and scientists have debated for years how it came about. In the latest attempt to find an explanation, researchers trained five chimps(黑猩猩)to walk on a treadmill(跑步機)while wearing masks that allowed measurement of their oxygen consumption. The chimps were measured both while walking upright and while moving on their legs and knuckles(膝關(guān)節(jié)).That measurement of the energy needed to move around was compared with similar tests on humans and the results are published in this week’s online edition of “Proceedings of the National Academy of Sciences”.
It turns out that humans walking on two legs use only one-quarter of the energy that chimps use while knucklewalking on four limbs(肢).And the chimps, on average, use as much energy using two legs as they did when they used all four limbs.
However, there were differences among chimps in how much energy they used, and this difference corresponded to their different manner of walking and anatomy(解剖構(gòu)造).One of the chimps used less energy on two legs, one used about the same and the others used more, said David Raichlen, assistant professor of anthropology at the University of Arizona.
“What we were surprised at was the variation(變異) ”, he said in a telephone interview. Interview. “That was pretty exciting, because when you talk about how evolution works, variation is the bottom line, without variation there is no evolution.”
Walking on two legs freed our arms, opening the door to drive the world, said Raichlen. “We think about the evolution of bipedalism as one of first events that led hominids(原始人)down the path to being humans.”
The research was supported by the National Science Foundation and the L.S.B.Leakey Foundation.
小題1: The underlined word “Bipedalism” in Paragraph 2 probably means____.

A．moving sideways	B．walking upright
C．walking on four legs	D．running fast

小題2:We can infer from the passage that____.

A．scientists have no idea on how humans’ walking on two legs came about

B．scientists have had different views on why chimps walk on four legs

C．scientists have had different views on how humans’ walking on two legs vame about

D．scientists have had similar views on how humans’ walking on two legs came about

小題3:What is Paragraph 4 mainly about?

A．How chimps saved energy.

B．Why chimps didn't walk on two legs.

C．David Raichlen studied chimps.

D．Different chimps consumed different energy.

小題4: According to the passage, humans walk upright in order to____.

A．conserve energy	B．differ from other animals
C．free their brains	D．strengthen their legs

Jurassic Park could become a reality with dinosaurs making a comeback after a discovery last week. Scientists found remains of a dinosaur’s blood vessels（血管）and cells .In theory, DNA from these cells could be used to clone the longdead dinosaur.
A team from North Carolina State University found the remains in a fossil(化石)of the leg bone of a Tyrannosaurus rex（暴龍）in Montana, US.
The last dinosaurs on Earth died some 65 million years ago, but they left bits of themselves behind wherever they lived. Around the world ,dug-up bones and fossils have given scientists many ideas about what the animals were like.
Preserved by minerals, the newly discovered leg bone was hard. So the scientists used a liquid to dissolve（溶解）the minerals. A week later, the remaining material was soft and stretchy（有彈性的）,which surprised the researchers.
Some of the materials appeared to be a network of blood vessels. Out of these, the researchers were able to squeeze(擠出)tiny , round, dark-red and deep-brown structures that seemed to be ancient blood cells.
Scientists are overjoyed by this discovery because most fossils come from hard body parts, like bones and shells, which last a long time. Soft tissues, like skin, muscle, and organs are very hard to find because they tend to break down more quickly.
Scientists think that the new discovery will help them to better understand how fossils form. Future finds should also help flesh out how the dinosaurs lived.
They were also very excited by the possibility of having some dinosaur DNA.From that scientists could create a real life “Jurassic Park”.
In the Hollywood movie, scientists reproduced dinosaurs from the DNA they found in a mosquito fossil and disaster soon followed.
小題1:Scientists are excited _________________________ .

A．because they have got dinosaur DNA

B．a(chǎn)bout making a movie called “Jurassic Park”

C．because they found the liquid to dissolve fossils

D．because it,s very hard to find soft tissues in fossils

小題2: The latest discovery can tell us       .

A．what the animals were like	B．how fossils form
C．how the dinosaur lived	D．how to get dinosaur DNA

小題3:What does the underlined phrase“flesh out”mean in the article?

A．a(chǎn)dd more details or information to	B．take more photos of
C．make the public know more about	D．find the answer to

小題4:Why is the latest discovery very important?

A．It could make it possible to make dinosaurs return to the former position.

B．It could throw light on how dinosaurs lived many years ago.

C．It could prove what dinosaurs were like.

D．It could explain why dinosaurs died some 65 million years ago.

  It's not a new phenomenon, but have you noticed how many nouns are being used as verbs? We all use them, often without noticing what we're doing.
I was arranging to meet someone for dinner last week, and I said “I’ll pencil it in my diary”, and my friend said “You can ink it in”, meaning that it was a firm arrangement not a tentative one!
Many of these new verbs are linked to new technology. An obvious example is the word fax, which is a shortening of facsimile originally, an exact copy of a book or document. We all got used to sending and receiving faxes, and then soon started talking about faxing something and promising we'd fax it immediately. So, nouns turn into verbs in two easy stages. Then along came email, and we were soon all emailing each other madly. How did we do without it? I can hardly imagine life without my daily emails.
Email reminds me, of course， of my computer and its software, which has produced another couple of new verbs. On my computer I can bookmark those pages from the World Wide Web that I think I'll want to look at again, thus saving all the effort of remembering their addresses and calling them up from scratch. I can do the same thing on my PC, but there I don't bookmark; I favorite—coming from “favorite pages”, so the verb is derived from an adjective not a noun． I wasn’t really sure whether people said this，but someone told me recently that they had favorited a site I was looking for and so they could easily give me its address.
In the late 1980s I noticed that lots of my friends had acquired pagers, and kept saying things like “I’ll page you as soon as I know what time we’re meeting”. They couldn't say it to me, though; 1 refused to have one． So my children bought me a mobile phone, now known simply as a mobile and I had to learn yet more new verbs. I can message someone, that is, I can leave a message （either spoken or written）for them on their phone．Or I can text them, write a few words suggesting when and where to meet, for example. How long will it be before I can mobile them, that is, phone them using my mobile? I haven’t heard that verb yet, but I’m sure I will soon. Perhaps I’ll start using it myself! 　
小題1:“I’ll pencil it in my diary” in the second paragraph probably means          .

A．it was a firm arrangement	B．it was an uncertain arrangement
C．the arrangement should be written as a diary	D．he prefers a pencil to a pen

小題2:A website address can be easily found if it has been＿____.

A．emailed

B．messaged

C．favorited

D．texted

小題3:Which of the following has not been used as a verb, yet?

A．message

B．page

C．email

D．mobile

小題4:The best title for this passage is____．

A．New Verbs from Old Nouns	B．The Development of the English language
C．New Technology and New words	D．Technology and Language.

High school dropouts（輟學者）earn an average of $ 9,000 less per year than graduates. Now a new study dispels a common belief why they quit. It’s much more basic than flunking out（不及格）.
Society tends to think of high school dropouts as kids who just can’t cut it. They are lazy，and perhaps not too bright．So researchers were surprised when they asked more than 450 kids who quit school about why they left.
“The vast majority actually had passing grades and they were confident that they could have graduated from high school.” John Bridgeland, the executive researcher said. About 1 million teens leave school each year. Only about half of African-American and Hispanic（美籍西班牙的）student will receive a diploma（證書），and actually all dropouts come to regret their decision. So， if failing grades don’t explain why these kids quit, what does? Again，John Bridgeland："The most dependable finding was that they were bored.” “They found classes uninteresting; they weren’t inspired or motivated. They didn’t see any direct connection between what they were learning in the classroom to their own lives, or to their career aspirations.”
The study found that most teens who do drop out wait until they turn sixteen, which happens to be the age at which most states allow students to quit. In the US，only one state，New Mexico，has a law requiring teenagers to stay in high school until they graduate. Only four states: California, Tennessee, Texas and Utah, plus the District of Columbia, require school attendance until age 18, no exceptions, another researcher，says raising the compulsory（義務(wù)的）attendance age may be one way to keep more kids in school．
　“As these dropouts look back，they realize they’ve made a mistake. And anything that sort of gives these people an extra push to stick it out and it through to the end, is probably helpful measure.”
New Hampshire may be the next state to raise its school attendance age to 18. But critics say that forcing the students unwilling to continue their studies to stay in school misses the point－the need for reform. It's been called for to reinvent high school education to make it more challenging and relevant, and to ensure that kids who do stick it out receive a diploma that actually means something. 　
小題1:Most high school students drop out of' school because＿＿．

A．they have failing grades	B．they take no interest in classes
C．they are discriminated against	D．they are lazy and not intelligent

小題2:Acceding to the passage，which state has a law requiring school attendance until they graduate?

A．New Hampshire

B．Utah

C．New Mexico

D．The District of Columbia

小題3:The underlined words “stick it out” probably means“＿＿”．

A．complete schooling	B．solve the problem
C．love having classes	D．believe in themselves

小題4:From the passage，we can infer the following EXCEPT that＿．

A．the grades of most dropouts at school were acceptable

B．a(chǎn)bout 500, 000 high school dropouts are black and Spanish

C．classes don't appeal to dropouts

D．on average dropouts cannot get good jobs

Antarctica and Environment
Antarctica has actually become a kind of space station – a unique observation post for detecting important changes in the world’s environment. Remote from major sources of pollution and the complex geological and ecological systems that prevail elsewhere, Antarctica makes possible scientific measurements that are often sharper and easier to interpret than those made in other parts of the world.
Growing numbers of scientists therefore see Antarctica as a distant-early-warning sensor, where potentially dangerous global trends may be spotted before they show up to the north. One promising field of investigation is glaciology. Scholars from the United States, Switzerland, and France are pursuing seven separate but related projects that reflect their concern for the health of the West Antarctic Ice Sheet – a concern they believe the world at large should share.
The Transantarctic Mountain, some of them more than 14,000 feet high, divide the continent into two very different regions. The part of the continent to the “east” of the mountains is a high plateau covered by an ice sheet nearly two miles thick. “West” of the mountain, the half of the continent south of the Americas is also covered by an ice sheet, but there the ice rests on rock that is mostly well below sea level. If the West Antarctic Ice Sheet disappeared, the western part of the continent would be reduced to a sparse cluster of island.
While ice and snow are obviously central to many environmental experiments, others focus on the mysterious “dry valley” of Antarctica, valleys that contain little ice or snow even in the depths of winter. Slashed through the mountains of southern Victoria Land, these valleys once held enormous glaciers that descended 9,000 feet from the polar plateau to the Ross Sea. Now the glaciers are gone, perhaps a casualty of the global warming trend during the 10,000 years since the ice age. Even the snow that falls in the dry valleys is blasted out by vicious winds that roars down from the polar plateau to the sea. Left bare are spectacular gorges, rippled fields of sand dunes, clusters of boulders sculptured into fantastic shapes by 100-mile-an-hour winds, and an aura of extraterrestrial desolation.
Despite the unearthly aspect of the dry valleys, some scientists believe they may carry a message of hope of the verdant parts of the earth. Some scientists believe that in some cases the dry valleys may soak up pollutants faster than pollutants enter them.
小題1:What is the best title for this passage?
A Antarctica and environmental Problems.
B Antarctica: Earth’s Early-Warning station.
C Antarctica: a Unique Observation Post.
D Antarctica: a Mysterious Place.
小題2:What would the result be if the West Antarctic Ice Sheet disappeared?
A The western part of the continent would be disappeared.
B The western part of the continent would be reduced.
C The western part of the continent would become scattered Islands.
D The western part of the continent would be reduced to a cluster of Islands.
小題3:Why are the Dry Valleys left bare?
A Vicious wind blasts the snow away.                B It rarely snows.
C Because of the global warming trend and fierce wind.  D Sand dunes.
小題4:Which of the following is true?
A The “Dry Valleys” have nothing left inside.
B The “Dry Valleys” never held glaciers.
C The “Dry Valleys” may carry a message of hope for the verdant.
D The “Dry Valleys” are useless to scientists.

A computer virus is a program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. All computer viruses are manmade. Here are some virus prevention tips.
Do not open any files attached to an e-mail from an unknown, suspicious or untrustworthy source.
Do not open any files attached to an e-mail unless you know what it is, even if it appears to come from a dear friend or someone you know. Some viruses can replicate（復(fù)制） themselves and spread through e-mail. Better be safe that sorry and confirm that they really sent it .
Do not open any files attached to an e-mail if the subject line is questionable or unexpected. If the need to do so is there always save the file to your hard drive before doing so.
Delete chain e-mails and junk e-mail. Do not forward（轉(zhuǎn)寄） or reply to any of them. These types of e-mail are considered spam（垃圾郵件）, which contains lots of annoying advertisements and useless information.
Do not download any files from strangers.
Be careful when downloading files from the Internet. Ensure that the source is a legitimate（合法的）and reputable one. Verify（證實）that an anti-virus program checks the files on the download site. If you are uncertain, don’t download the file at all or download the file to a floppy（軟盤）and test it with your own anti-virus software.
Update your anti-virus software regularly. Over 500 viruses are discovered each month, so you’ll want to be protected. These updates should be at least the products virus signature files. You may also need to update the product’s scanning engine as well.
Back up（備份） your files on a regular basis. If a virus destroys your files, at least you can replace them with your backup copy. You should store your backup copy in a separate location from your work files, one that is preferably not on your computer.
小題1:This passage mainly tells us              .

A．What a computer virus is

B．how to use e-mail safely

C．how to use computers safely

D．how to prevent computer viruses

小題2:Which of the following statements about computer virus is TRUE?

A．A computer virus is a kind of worm

B．Not all computer viruses are manmade

C．Computer viruses run according to our wishes

D．A computer virus is a program or piece of code.

小題3: When we use e-mail, we should                .

A．open all the files we receive

B．open any file even if we don’t know what it is

C．not open any files if the subject line is questionable

D．forward or reply to junk e-mail.

小題4:Which of the following statements is NOT true?

A．We’d better not down load any files from strangers.

B．We’d better download files from a legitimate and reputable source.

C．We should update our anti-virus software regularly.

D．We should store our backup copy in the same location as our work files.

Wild animals seem to have escaped the Indian Ocean tsunami(海嘯), adding weight to ideas they possess a “sixth sense” for disasters, experts said on Thursday.
Sri Lanka wildlife officials have said the giant waves that killed over 24,000 people along the Indian Ocean island’s coast seemingly missed wild beasts, with no dead animals found.
“No elephants are dead, not even a dead hare or rabbit. I think animals can sense disaster. They have a sixth sense. They know when things are happening,” H.D. Ratnayake, deputy director of Sri Lanka’s Wildlife Department, said on Wednesday.
The waves washed floodwaters up to 3 km (2 miles) inland at Yala National Park in the southeast, Sri Lanka’s biggest wildlife reserve and home to hundreds of wild elephants. “There has been a lot of evidence about dogs barking or birds migrating before volcanic eruptions or earthquakes. But it has not been proven,” said Matthew van Lierop, an animal behaviour specialist at Johannesburg Zoo.
“There have been no specific studies because you can’t really test it in a lab or field setting,” he said.
Other authorities agreed with this conclusion.
“Wildlife seem to be able to pick up certain phenomenon, especially birds. There are many reports of birds detecting coming disasters,” said Clive Walker, who has written several books on African wildlife.
Animals certainly rely on the known senses such as smell or hearing to avoid danger such as predators(食肉動物).
The idea of an animal “sixth sense” is a lasting one that the evidence on Sri Lanka’s damaged coast is likely to add to.
小題1:This passage is mainly about________.

A．the damage that was caused in the Indian Ocean tsunami

B．why animals can save them from natural disasters

C．how to protect the wildlife when disaster happens

D．the different opinions about animals’ natural power

小題2:Which of the following is true according to the text?

A．It has been proved that animals have a “sixth sense”.

B．Research has been made on the special movements of animals before disasters.

C．It’s generally considered that animals can sense the coming of disasters.

D．Animals have depended on the known senses to escape the Indian Ocean tsunami.

小題3:What does the term “sixth sense” in the text means?

A．It is the natural ability of animals that can save them from danger.

B．It is the animal’s imagination in the brain.

C．It is some hidden power to say in advance that something will happen.

D．It is a kind of sense that is the same as smell or hearing.

小題4:Which section does the text most probably appear in a newspaper?

A．News Report.

B．Discovery.

C．Science Fiction.

D．Culture.

The United States government wants to know what the public thinks about its findings on the safety of cloned animals.
The Food and Drug Administration says meat and milk from clones of adult cattle, pigs and goats are safe to eat. An F.D.A. official called them "as safe to eat as the food we eat every day." And when those clones reproduce sexually（有性繁殖）, the agency says, their offspring（后代） are safe to eat as well. But research on cloned sheep is limited. So the F.D.A. proposes that sheep clones not be used for human food.
The United States this year could become the first country to approve the sale of foods from cloned animals. First, however, the public will have ninety days to comment on three proposed documents. On December 28th the F.D.A. released a long report, called a draft risk assessment, along with two policy documents.
The agency says it must receive comments by April second. The F.D.A. seemed ready to act several years ago, but an advisory committee called for more research.
For now, the government will continue to ask producers to honor a request that they not sell foods from cloned animals.
Clones are still rare. They cost a lot and are difficult to produce.
The F.D.A. says most food from cloning is expected to come not from clones themselves, but from their sexually reproduced offspring. It says clones are expected to be used mostly as breeding animals to spread good qualities.
Public opinion studies show most Americans do not like the idea of food from cloned animals. But this research also shows the public knows little about cloning.
Cloning differs from genetic engineering. A cell taken from a so-called donor animals is grown into an embryo（胚胎）in the laboratory. Next, the embryo is placed into the uterus（子宮）of a female animal. If the process is successful, the pregnancy reaches full term and a genetic copy of the donor animal is born.
小題1:From the passage we know that               .

A．foods from cloned animals are popular in America

B．cloned adult animals are safe to eat except sheep.

C．cloned animals will be easy to produce

D．most foods from cloning is expected to take place of other foods

小題2:The main purpose of the text is to               .

A．tell a interesting story	B．give some advice on foods
C．give a report	D．compare different opinions

小題3:Who believe that foods from cloning are safe to eat?
A. Most Americans     B. An advisory committee
C. Critics             D. The F.D.A.
小題4:It can be inferred from the last paragraph that         .

A．cloning has much in common with genetic

B．not every cell taken from a donor animal can grow into a genetic copy

C．the donor animal should be a female one

D．cloned animals grow faster than normal ones

Early people had very little effect on the environment. They lived in caves in very small “clan” groups. They collected or killed only enough for the clan’s survival. Early clans were nomadic, which mean that they didn’t stay in one place. Instead, they moved around, following the animals that were their main food source and seeking areas where seasonal plants grew wild. Moving around seasonally helped to protect the environment. The land had time to recover and animals had time to breed (繁殖)before the clan returned for the next season..
As time went by, these small family clans joined with others to form larger groups for protection. Joining with other clans gave them more hunters and more women to help cut up the meat and share it between families. Eventually, people tamed(馴養(yǎng))wild animals such as dogs and horses. People settled around rivers and fertile plains to share responsibilities and duties. Then, people began to plant crops instead of moving to areas where the plants grew. This development changed the environment.
Traditional forms of work also changed. Some people were better at performing a particular task than other clan members, so then began to specialize in things they were good at doing. This also meant that they began to exchange their goods for things that others produced.
People began to communicate with distant tribes. Land was cleared for roads. Foreign plants and animals were transported to places where they had not existed before. Specialization also give people more free time. So art ,dance and music became important ways of expressing feelings and thoughts. This was how many great civilizations started.
Compared to the past, modern civilization has experienced many changes to become the highly developed society that exists today. Populations have increased rapidly. Forests have been cleared for farms. Inventions and technology have made work easier.
However, pollution and other serious problems have also resulted from human progress. As concerned citizens, it is up to us to learn from past mistakes and to help maintain and improve our environment.
小題1:Early tribes didn’t have much effect on animal population because_____
A .they kept animals for themselves         B they ate only vegetables
C they loved animals                     D they killed only enough for food
小題2:The main purpose for small clans to join together was_____
A to hurt animals                         B to seek safety
C to share caves                         D to protect environment
小題3:According to the passage ,we can learn that_____
A early people moved to new places looking for new sources of food
B modern civilization began when people started to live together in big groups
C modern advancements are always good for the environment
D people began to exchange goods because they didn’t have enough money
小題4:It can be concluded from the passage that_____
A human progress has brought civilization to the society
B civilization has improved traditional forms of work
C early people understood environmental protection
D our environment has been affected by human progress

Scientists have found what look like caves on Mars(火星), and say they could be protecting life from the planet’s terrible environment.
The first caves discovered beyond the Earth appear as seven mysterious black dots on the pictures sent back by NASA’s Mars Odyssey orbiter. Each as large as a football field, they may be openings into natural caves below the Martian surface.
“If there is life on Mars, there is a good chance you’d find it in caves,” said Jut Wynne, one of the researchers who noticed the features while working on a US Geological Survey Mars Cave Detection Program.
Jonathan Clarke, a geologist with the Mars Society of Australia, yesterday described the discovery as exciting.
One photo taken at night by an infrared imager(紅外線成像器) showed one hole to be unusually warm, suggesting hot air trapped during the day is flowing out.
“I said: ‘Wow, that’s a cave’” Dr. Clarke said excitedly. “People have been looking for these for a long time; now we have found them.”
He agreed such caves would be perfect places to hunt for life escaping from the bitterly cold, radiation-soaked(充滿輻射的), dry surface.
“Tiny drops of water could collect inside,” he said. “If there are gases coming out, they could provide energy for a whole range of bacteria. A cave is also a protection from radiation; the surface of Mars is exposed to high levels of space radiation.”
The caves probably formed when tube-shaped lave flows(管狀巖漿流) spread across the planet long ago. The outside of the tubes cooled, forming solid walls, while something hotter inside allowed the remaining have to flow out, forming caves. 
小題1:What does the passage mainly talk about?

A．How the caves were formed on Mars.	B．How scientists found these caves on Mars.
C．Caves on Mars may be full of hot air or a sign of life.
D．Scientists have completely recognized the surface of Mars.

小題2:We can learn from the passage that           .

A．water has already been found on Mars	B．the scientists found all the caves at night
C．it is certain that there is life in these caves
D．the surface of Mars is bitterly cold, radiation-soaked and dry

小題3:According to the passage, Dr. Clarke was so excited because        .

A．such caves could provide energy for life	B．they had finally found the caves on Mars
C．such caves would be perfect places to hunt for life
D．scientists had long been looking for these caves

小題4:Necessary conditions for life on Mars mentioned in the passage may include        .

A．lava and energy	B．water and radiation from space
C．gases and lava	D．water and protection from radiation