Why did humans evolve to walk upright? Perhaps because it’s just plain easier. M
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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(跑步机)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(膝关节).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(解剖构造).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(变异) ”, 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.
小题1: The underlined word “Bipedalism” in Paragraph 2 probably means____.| A．moving sideways | B．walking upright | | C．walking on four legs | D．running fast |
小题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 |
小题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. |
小题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 |
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答案
小题1:B
小题2:C
小题3:D
小题4:A |
解析
小题1:破折号后的内容即是对Bipedalism的解释，故B项正确。
小题2:由第二段第一句可知。
小题3:第四段主要讲了不同的黑猩猩直立行走所消耗的能量是不同的。
小题4:通过全文可知，人类直走的目的是为了减少能量的消耗。 |
举一反三
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（暴龙）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（有弹性的）,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(挤出)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.
小题1:Scientists are excited _________________________ .| A．because they have got dinosaur DNA | | B．about 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 |
小题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 |
小题3:What does the underlined phrase“flesh out”mean in the article?| A．add more details or information to | B．take more photos of | | C．make the public know more about | D．find the answer to |
小题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. |
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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!
小题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 |
小题2:A website address can be easily found if it has been＿____.| A．emailed | B．messaged | C．favorited | D．texted |
小题3:Which of the following has not been used as a verb, yet?| A．message | B．page | C．email | D．mobile |
小题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. |
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High school dropouts（辍学者）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（证书），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（义务的）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.
小题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 |
小题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 |
小题3:The underlined words “stick it out” probably means“＿＿”．| A．complete schooling | B．solve the problem | | C．love having classes | D．believe in themselves |
小题4:From the passage，we can infer the following EXCEPT that＿．| A．the grades of most dropouts at school were acceptable | | B．about 500, 000 high school dropouts are black and Spanish | | C．classes don"t appeal to dropouts | | D．on average dropouts cannot get good jobs |
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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.
小题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.
小题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.
小题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.
小题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（复制） 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（转寄） or reply to any of them. These types of e-mail are considered spam（垃圾邮件）, 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（证实）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（软盘）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（备份） 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.
小题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 |
小题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. |
小题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. |
小题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. |
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