Rivers are earthly arteries(要道) for the nutrients, deposits and freshwater that sustain healthy, diverse ecosystems. Their influence extends in multiple dimensions—not only along their length but belowground to aquifers(蓄水层) and periodically into nearby floodplains.
They also provide vital services for people by fertilizing agricultural land and feeding key fisheries and by acting as transportation corridors. But in efforts to ease ship passage, protect communities from flooding, and draw off water for drinking and irrigation, humans have increasingly constrained and broken these crucial water ways. “We try to control rivers as much as possible,” says Gunther Grill, a hydrologist at McGill University.
In new research published in May in Nature, Grill and his colleagues analyzed the barriers to 12 million total kilometers of rivers around the world. The team developed an index(指数) that evaluates six aspects of connectivity—from physical fragmentation (by dams, for example) to flow regulation (by dams or levees) to water consumption—along a river’s various dimension. Rivers whose indexes meet a certain threshold(临界值) for being largely able to follow their natural patterns were considered freeflowing.
The researchers found that among rivers longer than 1,000 kilometers (which tend to be some of those most important to human activities), only 37 percent are not blocked along their entire lengths. Most of them are in areas with a minimal human presence, including the Amazon and Congo basins and the Arctic. On the contrary, most rivers shorter than 100 kilometers appeared to flow freely—but the data on them are less comprehensive, and some barriers might have been missed. Only 23 percent of the subset of the longest rivers that connect to the ocean are uninterrupted. For the rest, human infrastructure is starving estuaries(河口) and deltas (such as the Mississippi Delta) of key nutrients. The world's estimated 2.8 million dams are the main cause, controlling water flow and trapping deposits.
The new research could be used to better understand how proposed dams, levees and other such projects might impact river connectivity, as well as where to remove these fixtures to best restore natural flow. It could also help inform our approach to rivers as the climate changes, says Anne Jefferson, a hydrologist at Kent State University, who was not involved in the work. Existing infrastructure, she says, “has essentially been built to a past climate that we are not in anymore and are increasingly moving away from.”
1.According to the passage, which of the following is NOT a function of rivers?
A.Easing ship passage. B.Fertilizing agricultural land.
C.Transporting people or goods. D.Sustaining healthy ecosystems.
2.What does the underlined word “constrained” in Paragraph 2 most probably mean?
A.Exhausted. B.Restricted.
C.Consumed. D.Expanded.
3.The underlined word “them” in Paragraph 4 refers to “________”.
A.earthly arteries B.human activities
C.entire lengths D.unblocked rivers
4.What does Anne Jefferson mean by the underlined sentence in the last paragraph?
A.Existing infrastructure has been perfectly built.
B.Existing infrastructure doesn't depend on the past climate.
C.Existing infrastructure determines the future climate.
D.Existing infrastructure doesn’t fit the changing climate.
高三英语阅读理解中等难度题
Rivers are earthly arteries(要道) for the nutrients, deposits and freshwater that sustain healthy, diverse ecosystems. Their influence extends in multiple dimensions—not only along their length but belowground to aquifers(蓄水层) and periodically into nearby floodplains.
They also provide vital services for people by fertilizing agricultural land and feeding key fisheries and by acting as transportation corridors. But in efforts to ease ship passage, protect communities from flooding, and draw off water for drinking and irrigation, humans have increasingly constrained and broken these crucial water ways. “We try to control rivers as much as possible,” says Gunther Grill, a hydrologist at McGill University.
In new research published in May in Nature, Grill and his colleagues analyzed the barriers to 12 million total kilometers of rivers around the world. The team developed an index(指数) that evaluates six aspects of connectivity—from physical fragmentation (by dams, for example) to flow regulation (by dams or levees) to water consumption—along a river’s various dimension. Rivers whose indexes meet a certain threshold(临界值) for being largely able to follow their natural patterns were considered freeflowing.
The researchers found that among rivers longer than 1,000 kilometers (which tend to be some of those most important to human activities), only 37 percent are not blocked along their entire lengths. Most of them are in areas with a minimal human presence, including the Amazon and Congo basins and the Arctic. On the contrary, most rivers shorter than 100 kilometers appeared to flow freely—but the data on them are less comprehensive, and some barriers might have been missed. Only 23 percent of the subset of the longest rivers that connect to the ocean are uninterrupted. For the rest, human infrastructure is starving estuaries(河口) and deltas (such as the Mississippi Delta) of key nutrients. The world's estimated 2.8 million dams are the main cause, controlling water flow and trapping deposits.
The new research could be used to better understand how proposed dams, levees and other such projects might impact river connectivity, as well as where to remove these fixtures to best restore natural flow. It could also help inform our approach to rivers as the climate changes, says Anne Jefferson, a hydrologist at Kent State University, who was not involved in the work. Existing infrastructure, she says, “has essentially been built to a past climate that we are not in anymore and are increasingly moving away from.”
1.According to the passage, which of the following is NOT a function of rivers?
A.Easing ship passage. B.Fertilizing agricultural land.
C.Transporting people or goods. D.Sustaining healthy ecosystems.
2.What does the underlined word “constrained” in Paragraph 2 most probably mean?
A.Exhausted. B.Restricted.
C.Consumed. D.Expanded.
3.The underlined word “them” in Paragraph 4 refers to “________”.
A.earthly arteries B.human activities
C.entire lengths D.unblocked rivers
4.What does Anne Jefferson mean by the underlined sentence in the last paragraph?
A.Existing infrastructure has been perfectly built.
B.Existing infrastructure doesn't depend on the past climate.
C.Existing infrastructure determines the future climate.
D.Existing infrastructure doesn’t fit the changing climate.
高三英语阅读理解中等难度题查看答案及解析
Rivers are the veins of the Earth, transporting the water and nutrients (营养物) needed to support the planet’s ecosystems, including human life. While many nutrients are essential to the survival of life, there is one element transported by water in rivers that holds the key to life and to the future of our planet — carbon.
Carbon is everywhere and understanding the way it moves and is either released or stored by the Earth system is a complex science in itself. Carbon starts its journey downstream when natural acid rain, which contains carbon dioxide from the atmosphere, melts minerals in rocks. This helps transform carbon dioxide to bicarbonate (碳酸氢盐) in the water that then flows in our rivers. This is a very long process, which is one of the main ways carbon dioxide is removed from the atmosphere. Carbon is transported by rivers to oceans and once that carbon reaches the ocean, it is stored naturally in deep sea sediments (沉淀物) for millions of years.
As carbon travels down a river, different processes may impact whether it continues to flow downstream or whether it is released into the atmosphere. For example, human engineering, like extensive dam construction, will result in dramatic changes to how water and sediments travel down the river. Some carbon that fails to reach the sea may return to the atmosphere in some way, which causes more warming.
Earth’s climate is closely related to the carbon cycle. We all know about the essential role of plants in consuming carbon dioxide, but do we know enough about rivers? Changing the chemistry and the course of rivers may have significant impacts on how they transport carbon. Remember: wherever we live, we all live downstream.
1.Where is the carbon in rivers originally from?
A.The atmosphere. B.The rocks.
C.The acid rain. D.The upstream areas.
2.Why is human engineering mentioned in Paragraph 3?
A.To show how important to life carbon is.
B.To explain how necessary it is to build dams.
C.To show how a natural process is interrupted.
D.To explain how humans fight global warming.
3.What does the author want to convey in the last paragraph?
A.We’d better move upstream to live.
B.We should protect plants along rivers.
C.We’d better seek more help from plants.
D.We should be cautious about river management.
4.What is the best title for the text?
A.What Humans Do with Rivers
B.How Rivers’ Transporting Carbon Counts
C.What the Carbon Cycle Means to Us
D.How Living Downstream Affects the Earth
高三英语中等难度题查看答案及解析
“Human influenza viruses can survive and be infectious for several days when they are deposited on banknotes,” according to the latest study by Yves Thomas and his colleages in Switzerland. Scientists put different types of flu virus onto Swiss franc notes and found that they could survive from a few hours to more than a week. The results depended on the type of flu virus.
According to the study, Swiss-banknotes are mostly cotton covered by a nonporous resin(无孔树脂). Banknotes from other countries may be composed of different materials, and this could affect viral transmission. “Whether similar results would be obtained with banknotes from other countries and with different characteristics needs to be studied.” the authors wrote. In an interview with Reuters, Thomas said. “Our studies have convinced us that it is possible to catch the flu from banknotes, but the chances are very, very small and there is no cause for concern among the gneral population,” To be sure, many kinds of frequently touched surfaces could temporarily hide the flu virus. Broadly speaking, scientists consider the risk of transmission in this way to be low. Particularly if hand-washing and other hygiene measures are practiced.
Three things must happen for a flu virus to be transmitted from one person to another via money. First, a person who is infected with the flu virus must sneeze or cough onto the banknote. Next, an uninfected person would need to touch the money while the virus si still present. Finally, that person would need to put his hand in his mouth or pick his nose, says Thomas. The best defense against infection: follow public health guidelines and wash your hands frequently.
49. What does the underlined word “this” refers to in the second paragraph?
A. The time when people stay in a bank.
B. The fact that banknotes may consist of deferent materials.
C. The bank where people draw their money.
D. The country where the banknotes are in circlation.
50. From the last paragraph, we can know that an infected person should ________.
A. pay attention to his personal hygiene B. wash his hands after leaving a bank
C. be monitored at a bank D. not cough at a bank
51. What can we learn from the passage?
A. Any person who touches banknotes will become infected.
B. Different flu viruses stay on the surface of banknotes for different lengths of time.
C. The bank should not allow any infected person to enter.
D. Only banknotes in Switzerland can transmit the flu virus.
52. What is the best title for the passage?
A. Is it Dangerous to Stay in a Bank?
B. How to Avoid Being Infected with the Flu Virus?
C. Can You Catch the Flu from Handling Money?
D. Why Do People Refuse to Use Banknotes in Switzerland?
高三英语阅读理解简单题查看答案及解析
Planet Earth would be a scary place for humans if dinosaurs still ruled the world.
Though there are still some traces of life from the Jurassic Period, the Age of Dinosaurs more than 65 million years ago.
This mass extinction is believed to be the result of an asteriod(小行星)hitting Earth. A new report by the journal Biological Reviews called " The Extinction of Dinosaurs” concludes that this impact was, indeed, the cause of the dinosaurs’ demise. But the space blast(爆炸) wasn't the only reason these creatures aren't still around today.
Dinosaurs need food to survive. Meat-eating monsters like the Tyrannosaurus Rex(霸王龙) were at the top of the food chain, and fed off plant eaters like the horned Triceratops (三角恐龙). These herbivores (食草动物) were decreasing in population after the asteroid hit Earth, which left the meat-eating species less food to survive on. “In any ecosystem where you remove links to key species, that community has problems," Richard Butler, one of the review's authors, told National Ceographic.
While the herbivore population was going down, Earth's temperatures were rising when volcanoes erupted. Hot vapors and gases began wiping out some of the dinosaur population and weakening the survivors.
These changes made the asteroid's impact especially powerful. It caused more volcanoes to erupt, heated up Earth's atmosphere, and led to a sharp drop in the level of oxygen in the oceans.
With the dinosaurs gone, mammals(哺乳动物) began to evolve into bigger and more diverse species. Many animals we see today, like birds, sharks, and even some cats and dogs, appeared after the asteroid hit Earth. But none rule Earth quite like the dinosaurs did..
1. Which of the following words can replace the underlined word’’ demise" in Paragraph 2?
A. Death. B. Evolvement.
C. Presence. D. Decrease.
2. According to what Richard Butler said, what caused dinosaurs to die out?
A. A shortage of clean water.
B.A break in the food chain.
C. A small variety of animals.
D. The constant warming climate.
3. What was the negative effect of the asteroid hitting Earth?
A. Oceans became too hot for animals.
B. There was less oxygen in the oceans.
C. Earth's climate became violent.
D. The majority of the plants gradually died out.
4. The text is mainly about .
A.the evolvement of mammals on Earth
B.the gradual process of climate change
C.the importance of the balance of ecosystem
D.the cause of the extinction of the dinosaurs
高三英语阅读理解困难题查看答案及解析
______ most of us are satisfied with the nutrients we’re getting from our diets, they are actually far from enough.
A.While B.If C.Since D.Before
高三英语单项填空简单题查看答案及解析
As oil is running out on the earth, we are in need of searching for other _____ energy resources.
A. alternative B. abundant
C. creative D. automatic
高三英语单项填空中等难度题查看答案及解析
Teenagers who do not get enough of the nutrients commonly found in fruits and fish are easier to have bad lungs, coughing and wheezing (喘息).Teens who eat the least of fruit and especially vitamin C have weaker lungs compared to the others.
Teens who take in less vitamin E, found in vegetable oil and nuts, are more likely to have asthma(哮喘), Jane Bums at the Harvard School of Public Health found.
Based on these findings.Bums said that current recommended dose(一剂)of vitamin C, 85 mg a day, may not be enough for teens to have healthy lungs.Teens who eat less fruit and don't take in enough fatty acids (脂肪酸) are more likely to have asthma and the signs of breathing difficulty.
Proper amounts of fatty acids are protective, Bums said, though fish, the best source of fatty acids, is particularly unpopular with teenagers.Fatty acids are also found in some nuts as well as some green vegetables'.Smokers who avoid vitamin C will increase their chances of coughing, wheezing and developing phlegm(痰).
More than 80 percent of teens are getting their recommended doses of vitamin C - mainly from fruit drinks."I wouldn't approve of drinking them, but at least they're getting their vitamin C from somewhere," Burns said.
Burns added that there are several different ways to get the necessary nutrients."I think vitamin supplements are fine.I think adding vitamin D to orange juice is fine.But I do think there are added benefits that we don't fully understand of eating whole foods like fruits and vegetables and fish," she said.The researchers did not account for poverty and other factors that often distinguish less-healthy eaters and may explain their findings.
1.According to the passage, what is the problem with teens who don't get enough nutrients?
A.They are becoming smokers. B.They don't take enough exercise.
C.They eat too much fruit and fish. D.They are likely to have weaker lungs.
2.According to Burns, how should teens get the necessary nutrients?
A.By drinking juice as much as possible.
B.By eating more whole foods.
C.By taking vitamin pills.
D.By giving up smoking.
3.Which of the following is NOT mentioned by the researchers in the passage?
A.The amount of nutrients teens should take in a day.
B.How teens can take in enough nutrients.
C.Whether poor teens can prove their findings.
D.The fact that teens don't like fish.
4.What is the best title for the passage?
A.Poor nutrition hurts teens' health. B.Teens lack proper nutrition.
C.Teens are easy to suffer from diseases. D.More fruit help keep teens healthy.
高三英语阅读理解中等难度题查看答案及解析
Rivers are one of our most important natural resources. Many of the world’s great cities are located on rivers, and almost __1_______ country has at least one river __2_______(flow) through it that plays __3________ important part in the lives of its people.
Since the beginning of history, people _4______________ (use) rivers for transportation. The longest one in the United States is the Mississippi, and the lifeline of Egypt is the Nile. __5_____________ transportation, rivers give water to drink, water for crops, and chances for fun and recreation (消遣,娱乐活动)for the people __6________________ live along their banks.
However, large cities and industries that are located on rivers often make problems. As the cities grow __7____________ size and industries increase in number, the water in the rivers becomes __8_____________ (pollute) with chemicals and other materials. People come to kwon the __9_____________ (important) of doing more to keep their rivers clean __10_____________ they want to enjoy the benefits of this natural resource.
高三英语填空题简单题查看答案及解析
287. The clear colorless liquid that falls as rain, fills lake and rivers, and is necessary for life to exist is______.
A.oxygen | B.petrol | C.water | D.Flood |
高三英语单项填空简单题查看答案及解析
(2013·江西十所重点中学高三二模)Many people headed for the water to ________, including rivers, bays in the seaside of the country.
A.put off B.cut off
C.pull off D.cool off
高三英语单项填空中等难度题查看答案及解析