Scientists have solved the mystery of why the overwhelming majority of mammoth fossils(化石)are male.
Much like wild elephants today, young male Ice Age mammoths probably travelled around alone and more often got themselves into risky situations where they were swept into rivers, or fell through ice or into mud, lakes or sinkholes that preserved their bones for thousands of years, scientists say.
Females, on the other hand, travelled in groups led by an older matriarch who knew the landscape and directed her group away from danger.
"Without the benefit of living in a herd led by an experienced female, male mammoths had a much higher risk of dying in natural traps such as mud holes, rock cracks and lakes, "said co-author Love Dalen of the Swedish Museum of Natural History in a report published on Thursday in the journal Current Biology.
The study used genetic data to determine the sex of 98 woolly mammoth fossils in Siberia Researchers found that 69% of the samples were male, a heavily unbalanced sex ratio, assuming that the sexes were fairly even at birth.
"We were very surprised because there was no reason to expect a sex bias in the fossil record," said first author Patricia Pecnerova, also of the Swedish Museum of Natural History. Therefore, researchers believe that something about the way they lived influenced the way they died.Most bones, tusks, and teeth from mammoths and other Ice Age animals haven't survived," explained Dalen.
"It is highly likely that the remains that are found in Siberia these days have been preserved because they have been buried, and thus protected from weathering."
These giant, tusked plant eaters disappeared about 4,000 years ago. While there is no scientific agreement about the causes of their disappearance from the planet, most believe that climate change, excessive hunting by humans and the spread of other animals into mammoth feeding grounds were influential factors.
1.The underlined word "matriarch" in paragraph 3 means _______.
A. figure head B. female leader
C. experienced animal D. mature mammoth
2.Why do the majority of mammoth fossils come from male animals?
A. Scientists find it easier to study male fossilized bones.
B. There were more male mammoths in comparison to females
C. Male mammoths were better able to adapt to the changing circumstances.
D. Male mammoths more frequently died in places where fossils could form.
3.Which of the following is suggested as a reason for mammoths dying out?
A. The increasing competition for food.
B. The cooling of the earth's temperature.
C. The disappearance of male mammoths.
D. The risky behaviour of younger mammoths.
4.What is the text type of the passage?
A. A newspaper article. B. An academic essay.
C. A historical description. D. A science fiction story.
高三英语阅读理解困难题
Scientists have solved the mystery of why the overwhelming majority of mammoth fossils(化石)are male.
Much like wild elephants today, young male Ice Age mammoths probably travelled around alone and more often got themselves into risky situations where they were swept into rivers, or fell through ice or into mud, lakes or sinkholes that preserved their bones for thousands of years, scientists say.
Females, on the other hand, travelled in groups led by an older matriarch who knew the landscape and directed her group away from danger.
"Without the benefit of living in a herd led by an experienced female, male mammoths had a much higher risk of dying in natural traps such as mud holes, rock cracks and lakes, "said co-author Love Dalen of the Swedish Museum of Natural History in a report published on Thursday in the journal Current Biology.
The study used genetic data to determine the sex of 98 woolly mammoth fossils in Siberia Researchers found that 69% of the samples were male, a heavily unbalanced sex ratio, assuming that the sexes were fairly even at birth.
"We were very surprised because there was no reason to expect a sex bias in the fossil record," said first author Patricia Pecnerova, also of the Swedish Museum of Natural History. Therefore, researchers believe that something about the way they lived influenced the way they died.Most bones, tusks, and teeth from mammoths and other Ice Age animals haven't survived," explained Dalen.
"It is highly likely that the remains that are found in Siberia these days have been preserved because they have been buried, and thus protected from weathering."
These giant, tusked plant eaters disappeared about 4,000 years ago. While there is no scientific agreement about the causes of their disappearance from the planet, most believe that climate change, excessive hunting by humans and the spread of other animals into mammoth feeding grounds were influential factors.
1.The underlined word "matriarch" in paragraph 3 means _______.
A. figure head B. female leader
C. experienced animal D. mature mammoth
2.Why do the majority of mammoth fossils come from male animals?
A. Scientists find it easier to study male fossilized bones.
B. There were more male mammoths in comparison to females
C. Male mammoths were better able to adapt to the changing circumstances.
D. Male mammoths more frequently died in places where fossils could form.
3.Which of the following is suggested as a reason for mammoths dying out?
A. The increasing competition for food.
B. The cooling of the earth's temperature.
C. The disappearance of male mammoths.
D. The risky behaviour of younger mammoths.
4.What is the text type of the passage?
A. A newspaper article. B. An academic essay.
C. A historical description. D. A science fiction story.
高三英语阅读理解困难题查看答案及解析
Why do people like what they like? Scientists have taken on the task of solving this mystery(奥秘)for ages. In the 1960s, psychologist Robert Zajonc conducted a series of experiments where he showed people nonsense words and random shapes. Afterward he asked his subjects which they preferred out of ever thing they had been shown. In study
after study, people always chose the words and shapes they had seen the most. Their preference was for familiarity.
This discovery was one of the most important findings in modern psychology. But the preference for familiarity has clear limits. People get tired of even their favorite songs and movies. On one hand, humans seek familiarity, because it makes then feel safe. On the other hand, people love the thrill of something new. This change between familiarity and discovery affects ns all the time- not just our preferences for pictures and songs, but also our preferences for ideas and even people.
For that reason, the power of familiarity seems to be strongest when a person isn’t expecting it. The opposite is also true: A surprise seems to work best when it contains some familiarity. Nobody knows this better than Raymond Loews, who is considered to be the "father of industrial design. He had a theory that he said could help artists sell anything to anyone. He called it MAYA --"Most Advanced Yet Acceptable""To sell something surprising, make it familiar; and to sell something familiar, make it surprising," he said.
One of Loewy’s final tasks was too add an element(要素)of familiarity to a truly new invention: NASA’s first space station. Loewy’s biggest contribution to the space station was that he insisted NASA install a window with a view of Earth. Today, tens of millions of people have seen this small detail in films about astronauts. It is hard to imagine a more perfect example of MAYA: a window to a new world can also show you home.
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高三英语提纲类作文中等难度题查看答案及解析
According to The Sun, British scientists have solved the ancient riddle of ________ came first—chicken or egg?
A. who B. what
C. which D. that
高三英语单项填空困难题查看答案及解析
The police have finally ______ the mystery (疑案).
A. succeeded to solve B. succeeded in solving
C. succeeded solving D. succeeded on solving
高三英语单项填空简单题查看答案及解析
Strange ice rings in Siberia’s Lake Baikal have puzzled scientists for decades, but now the mystery apparently has been solved. The answer: the rings are caused by warm, circular currents of water under the ice, called eddies (漩涡).
The eddies’ strong currents melt the ice at the edge, but weaker ones keep the center frozen. “Results of our field surveys show that there are warm eddies that circulate in a clockwise (顺时针的) direction under the ice cover,” said Alexei Kouraev, a hydrologist at the University of Toulouse, in a NASA statement. “In the eddy center, the ice does not melt — even though the water is warm — because the currents are weak,” he said. “But on the eddy boundary, the currents are stronger, and warmer water leads to rapid melting.”
During field work, Kouraev and his colleagues drilled holes near ice rings and set sensors capable of measuring the temperature and salinity (盐浓度) of the water to a depth of 700 feet. They found that the water in the eddies was 2 to 4 ℉ warmer than the surrounding water.
Most of the rings appear in March or April and have a width of about 3 to 4 miles — too big to recognize from the ground but easily seen from satellites above. Some rings were ephemeral while others lasted for weeks or even months.
Lake Baikal is the world’s largest and deepest freshwater lake, according to Gizmodo. It’s home to many varieties of fish not seen anywhere else in the world, and even a population of freshwater seals.
Researchers are still investigating what causes Baikal’s eddies but think it’s likely because of wind patterns, rivers that flow into the lake and the shape of the lake’s coastline and bottom.
1.Which word can best replace the underlined word “ephemeral” in paragraph 4?
A.Steady. B.Current.
C.Fundamental. D.Temporary.
2.Why is the ice in the center of ice rings frozen while that at the edge is melted?
A.Because the center of ice rings is 2 to 4℉ warmer than the edge.
B.Because the currents in the center are less powerful.
C.Because it is too wide to be recognized or melted.
D.Because water in the center circulates in a clockwise direction.
3.Which of the following statements about Lake Baikal’s eddies is TRUE?
A.They are caused by hot and circular currents under the ice.
B.The ice in the center of Lake Baikal’s eddies melts faster than that of the edge.
C.Researchers are uncertain about the exact reason of the eddies’ existence.
D.Lake Beikal’s eddies can only be measured at the depth of 700 feet.
4.What maybe the best title for the passage?
A.What’s causing the giant ice rings in Siberia?
B.The mystery of the eddies' in the Lake Baikal uncovered.
C.The largest and deepest freshwater lake — Lake Baikal.
D.Why does the edge of an ice ring melt faster?
高三英语阅读理解中等难度题查看答案及解析
Why elephants rarely get cancer is a mystery that has confused scientists for decades. A study led by researchers at Huntsman Cancer Institute (HCI), at the University of Utah and Arizona State University may have found the answer.
According to the results, elephants have 38 additional modified copies of a gene that encodes p53, a definite tumor suppressor, as compared to humans, who have only two. Further, elephants may have a more powerful mechanism for killing damaged cells that are at risk for becoming cancerous. In isolated elephant cells, this activity is doubled compared to healthy human cells, and five times that of cells from patients with Li-Fraumeni Syndrome, who have only one working copy of p53 and more than a 90 percent lifetime cancer risk in children and adults. The results suggest extra p53 could explain elephants’ increased resistance to cancer.
“Nature has already figured out how to prevent cancer. It’s up to us to learn how different animals overcome the problem so we can adapt those strategies to prevent cancer in people,” says co-senior author Joshua Schiffman, M.D., pediatric oncologist (儿科肿瘤医生) at Huntsman Cancer Institute, University of Utah School of Medicine.
But Prof Mel Greaves, from the Institute of Cancer Research in London, says we should focus on why humans have such high levels of cancer. He pointed to the rise of unhealthy, cancer-causing behaviors, such as obesity and sunbathing. “You’ve never seen an elephant smoke!” he added.
According to Schiffman, elephants have long been considered a walking problem. Because they have 100 times as many cells as people, they should be 100 times more likely to have a cell slip into a cancerous state and cause the disease over their long life span of 50 to 70 years. And yet analysis of a large database of elephant deaths estimates a cancer death rate of less than 5 percent compared to 11 to 25 percent in people.
1.Why are elephants less likely to get cancer than humans?
A.Elephants are bigger than humans.
B.Elephants have more p53 genes and mechanism killing damaged cells.
C.Elephants are not as clever as humans in walking.
D.Elephants eat more than humans.
2.Which of the following can be the equivalent of the underlined word “suppressor”?
A.multiplier B.complex C.restrainer D.coordinator
3.What’s Prof Mel Greaves’ attitude towards the discovery?
A.Doubtful. B.Neutral. C.Critical. D.Favorable.
4.What can we infer from the last paragraph?
A.Elephants have longer life than people.
B.There is no chance that elephants die from cancer.
C.The rate of elephants dying from cancer is increasing.
D.It was thought theoretically that elephants could get cancer more easily.
高三英语阅读理解中等难度题查看答案及解析
Choosing a major, which is the specialized area of your college study, can be overwhelming. But have no fear! Your choice of major will not lock you into a specific career for the rest of your life. And the major you choose will neither predict nor guarantee your future. Consider these factors when picking your major.
Career Prep
Choose a major because it will prepare you for a specific career path or advanced study. Maybe you already know that you want to be a nurse, a day trader, or a web developer. Before you declare, take a class or two in the relevant discipline, check out the syllabus for an advanced seminar, and talk to students in the department of your choice. Make sure you’re ready for the coursework required for the career of your dreams.
Earning Potential
Future earning potential is worth considering—college is a big investment, and while college can pay you back in many ways beyond salary, this can be a major factor for students who are paying their own way or taking out loans. According to PayScale.com, the majors that lead to the highest salaries include just about any type of engineering, actuarial mathematics, computer science, physics, government, and economics. Keep your quality of life in mind, too—that six figure salary may not be worth it if you're not happy at the office.
Subjects You Love
Some students choose a major simply because they love the subject matter. If you love what you're studying, you're more likely to fully engage with your classes and college experience, and that can mean better grades and great relationships with others in your field. If your calling is philosophy, don't write it off just because you're not sure about graduate school, or what the job market holds for philosophers. Many liberal arts majors provide students with critical thinking skills and writing abilities that are highly valued by employers.
Undecided? Explore your interests.
If you truly have no idea what you want to study, that's okay—many schools don't require students to declare a major until you are a second-year student. That gives you four semesters to play the field. Exploring your interests will help you find your best fit major—and maybe even your ideal career.
1.You don’t need to feel fearful when choosing your major because ______.
A.your major has completely nothing to do with your future
B.you are not limited to only one particular career for your whole life
C.changing career fields are unavoidable in your life
D.you only spend a little time on whatever subject you choose
2.The underlined word discipline is closest in meaning to ______.
A.field B.rule
C.theory D.knowledge
3.What do we learn about from Para. 3?
A.Your college investment will be all given back to you in the form of high salary.
B.Future career earning is viewed as the top concern for most college students.
C.High salary will not be worthwhile at the cost of your unhappy office work.
D.If you choose engineering-related majors, you are sure to earn high salary.
4.What can we infer from the passage?
A.You are advised to choose liberal arts majors for what are provided.
B.Worse grades result from poor relationships with others in college.
C.Employers like liberal arts majors more than science majors in job market.
D.Some students don’t necessarily need to decide their choices of majors upon entering college.
5.What is the passage mainly about?
A.Why is it difficult to choose a major. B.What influences your choice of a major.
C.How can a major affect your career. D.When should you decide your major.
高三英语阅读理解中等难度题查看答案及解析
It remains a curiosity and a bit of a historical mystery why we don't all drive on the same side of the road. The fact is that most people are right-handed; that's why, for much of history, drivers have stuck to the left. Ancient Romans using two-wheeled carriages are believed to have held the reins(缰绳) with their right hands and a whip with their left; to avoid whipping the near drivers, they favored the left-hand side the road. It's also easier for right-handers to get on a horse from the left, so riders were attracted to that side to avoid the near traffic as they climbed on and off. Finally, knights(骑士) and the other drivers favored the left so they could do battle, if necessary, with their good hand.
So why does most of the world travel on the right side today? Theories differ, but there's no doubt Napoleon was a major influence. The French have used the right since the late 18th century. Some say that before the French Revolution, people in upper class drove their carriages on the left, forcing the peasantry to the right. During the violence, fearful rich people sought to mix with the peasantry by traveling on the right as well. Regardless of the origin, Napoleon brought right-hand traffic to the nations he conquered, including Russia, Switzerland and Germany. Hitler, in turn, ordered right-hand traffic in Czechoslovakia and Austria in the 1930s. Nations that escaped right-handed conquest, like Great Britain, kept their left-handed tradition.
1.Who had a major effect on “keep-right” traffic law?
A. Ancient Romans B. Hitler
C. Napoleon D. Austrians
2. What does the second paragraph mainly tell us?
A. Napoleon brought right-hand traffic to the nations he conquered.
B. Hitler ordered right-hand traffic in Austria.
C. Great Britain escaped right-handed conquest.
D. The reasons that most of the world drives on the right side.
3.What does the word peasantry in the last paragraph mean?
A. People in upper class.
B. Right-handers.
C. Drivers.
D. Poor people.
4. Apart from Great Britain, which country mentioned in the text keeps left-hand
traffic?
A. France B. Ancient Rome
C. Russia D. Germany
高三英语阅读理解中等难度题查看答案及解析
It is a mystery that has puzzled doctors for decades. But experts believe they have now finally solved the tricky question of why winter is notoriously known as the flu season.
According to a new research, the influenza virus coats itself in a protective fatty shield that is tough enough to resist cold temperatures. The butter-like material only melts when it hits the respiratory tract（呼吸道）, leaving the virus free to infect cells-- a process scientists say is like an M&M melting in the mouth.
However, in warmer outdoor temperatures, the protective coating melts before it reaches a person or an animal, killing the bacteria before they can infect someone. Joshua Zimmerberg, from the National Institute of Child Health and Human Development (NICHD), in the US, which led the study, said: “Like an M&M in your mouth, the protective covering melts when it enters the respiratory tract. It's only in this liquid period that the virus is able to enter a cell to infect it.”
In the past, scientists worked on theories that flu is more common in winter because people spend more time inside or the radiation from the sun in summer kills off germs. But no research successfully explained the spread of the disease.
Researchers have already claimed that the report, which is published in the journal Nature Chemical Biology, could lead to new ways to prevent and treat flu. “Now that we understand how the flu virus protects itself so that it can spread from person to person, we can work on ways to prevent it.”
Influenza and other respiratory viruses are spread in small drops broadcast by coughing, sneezing and talking and which can also settle onto surfaces, to be picked up on fingertips.
1. What can be the best title of the passage?
A. The mystery that has puzzled doctors for decades. B. New ways to prevent and treat flu.
C. A discovery of how flu strikes in Winter. D. Ways found to prevent flu.
2. Which of the following statements is NOT true?
A. Doctors have been trying hard to discover why flu strikes in winter.
B. In the past, scientists didn’t know how flu spreads.
C. It is possible that flu virus will no longer threaten humans in winter.
D. People get affected by flu because they spend much more time inside in winter.
3. Where should you insert the following paragraph into the passage?
Duane Alexander, the director of NICHD, said: “The study results open new avenues of research for thwarting (使…受挫)winter flu outbreaks.”
A. Between Paragraphs 1 and 2. B. Between Paragraphs 3 and 4.
C. Between Paragraphs 4 and 5. D. Between the last two paragraphs.
4.In what process or order does flu occur?
a. The virus infects cells b. The influenza virus was born
c. The butter-like material melts d. The virus hits respiratory tract
e. The virus coats itself in butter-like shield f. The virus is free
A. a, c, d, e, b, f . B. c, f, d, b, e, a. C. b, e, d, c, f, a. D. d, b, e, c, f, a.
高三英语阅读理解简单题查看答案及解析
Scientists have advanced many theories about why human beings cry tears , none of ______ has been proved.
A. whom B. which C. what D. that
高三英语单项填空中等难度题查看答案及解析