Twothirds of the world's major rivers have now been disrupted with more than 50,000 dams in an attempt to store water and provide power.In the US,there are more than 85,000 dams,disrupting large and small rivers,and in most cases transforming natural flow.The most famous of these,the Hoover Dam,constructed in the 1930s,is mainly responsible for the fact that the Colorado River no longer reaches the ocean.
Dams,besides all their attractive benefits,also have negative impacts.Creating a reservoir means a large area must be flooded.Communities may lose their land,houses and culturally important sites.
Environmentally,the new reservoir can be a paradise for wildlife,especially birds;however,it can cause greenhouse gas emissions and poison the water.Also,the dramatic rise and fall of water levels during dam releases is too extreme for plants and animals to cope with,resulting in dead zones around the shores of reservoirs.Fish that lay their eggs in the shallows,for example,may find a few hours later that those sites are high and dry.
Downstream(在下游方向)of a dam,the flow may be reduced so that farmers cannot irrigate their fields.Many rivers run through national borders,which may cause conflict over precious water.Disputes have been continuing between India and Pakistan,and Turkey,Syria and Iraq,for example.
Dams don't just block the flow of water.They also prevent fish migrations,and dams are a barrier to sediment(沉淀物)flows.Instead of rushing downriver,sediments get backed up against the dam wall,which causes the reservoir level to increase over time.However,sediments which are rich in nutrients have become a problem.The fertility of the entire system can be influenced,with soils lost during seasonal rains not being replaced.
Perhaps the biggest problem can be seen in deltas,which are sinking into the oceans.Groundwater is being extracted to feed the city,causing the city to sink,and sediments washed away by the ocean are no longer being replaced.The result is that sea level rises in cities from Shanghai to Alexandria.
1.The Hoover Dam is mentioned in the passage in order to show________.
A.dams play an important role in our life
B.dams have impacted the flow of the rivers
C.dams make people lose their land and houses
D.dams have many benefits as well as side effects
2.What effects does creating a reservoir have on people's life?
a.People will see fewer birds on the sides of the rivers.
b.Farmers will have less water to irrigate their fields.
c.Visitors can't visit some cultural relics any more.
d.More conflicts and wars over water will break out.
e.More kinds of fish will become extinct in future.
A.a,c B.c,e
C.b,e D.b,c
3.With many dams built across the rivers,fish ________.
A.will find more places to lay their eggs
B.will face a dangerous habitat
C.will be fed on more sediments rich in nutrients
D.will find it easier to deal with the rise of water
4.How can dams influence large cities like Shanghai?
A.Their entire system will be influenced.
B.The rainy season will last longer.
C.They will lie below sea level in future.
D.Rich soils will be washed away.
5.What does the passage mainly talk about?
A.Environmental loss of dams.
B.Cultural loss of dams.
C.Economic gain of dams.
D.Environmental benefits of dams.
高三英语阅读理解中等难度题
Twothirds of the world's major rivers have now been disrupted with more than 50,000 dams in an attempt to store water and provide power.In the US,there are more than 85,000 dams,disrupting large and small rivers,and in most cases transforming natural flow.The most famous of these,the Hoover Dam,constructed in the 1930s,is mainly responsible for the fact that the Colorado River no longer reaches the ocean.
Dams,besides all their attractive benefits,also have negative impacts.Creating a reservoir means a large area must be flooded.Communities may lose their land,houses and culturally important sites.
Environmentally,the new reservoir can be a paradise for wildlife,especially birds;however,it can cause greenhouse gas emissions and poison the water.Also,the dramatic rise and fall of water levels during dam releases is too extreme for plants and animals to cope with,resulting in dead zones around the shores of reservoirs.Fish that lay their eggs in the shallows,for example,may find a few hours later that those sites are high and dry.
Downstream(在下游方向)of a dam,the flow may be reduced so that farmers cannot irrigate their fields.Many rivers run through national borders,which may cause conflict over precious water.Disputes have been continuing between India and Pakistan,and Turkey,Syria and Iraq,for example.
Dams don't just block the flow of water.They also prevent fish migrations,and dams are a barrier to sediment(沉淀物)flows.Instead of rushing downriver,sediments get backed up against the dam wall,which causes the reservoir level to increase over time.However,sediments which are rich in nutrients have become a problem.The fertility of the entire system can be influenced,with soils lost during seasonal rains not being replaced.
Perhaps the biggest problem can be seen in deltas,which are sinking into the oceans.Groundwater is being extracted to feed the city,causing the city to sink,and sediments washed away by the ocean are no longer being replaced.The result is that sea level rises in cities from Shanghai to Alexandria.
1.The Hoover Dam is mentioned in the passage in order to show________.
A.dams play an important role in our life
B.dams have impacted the flow of the rivers
C.dams make people lose their land and houses
D.dams have many benefits as well as side effects
2.What effects does creating a reservoir have on people's life?
a.People will see fewer birds on the sides of the rivers.
b.Farmers will have less water to irrigate their fields.
c.Visitors can't visit some cultural relics any more.
d.More conflicts and wars over water will break out.
e.More kinds of fish will become extinct in future.
A.a,c B.c,e
C.b,e D.b,c
3.With many dams built across the rivers,fish ________.
A.will find more places to lay their eggs
B.will face a dangerous habitat
C.will be fed on more sediments rich in nutrients
D.will find it easier to deal with the rise of water
4.How can dams influence large cities like Shanghai?
A.Their entire system will be influenced.
B.The rainy season will last longer.
C.They will lie below sea level in future.
D.Rich soils will be washed away.
5.What does the passage mainly talk about?
A.Environmental loss of dams.
B.Cultural loss of dams.
C.Economic gain of dams.
D.Environmental benefits of dams.
高三英语阅读理解中等难度题查看答案及解析
Plans have been proposed ______ the largest dam in the world to be built along the Congo river.
A.of B.with C.for D.on
高三英语单项填空中等难度题查看答案及解析
Plans have been proposed ___ the largest dam in the world to be built along the Congo river.
A.of B.with
C.for D.on
高三英语单项填空中等难度题查看答案及解析
The construction of the two new railway lines by now.
A.have been completed B.has been completed C.has coompleted D.have completed
高三英语单项填空中等难度题查看答案及解析
25.The construction of the two new railway lines____by now.
A.has been completed | B.have been completed |
C.has completed | D.have completed |
高三英语单项填空简单题查看答案及解析
The construction of the two new railway lines _______by now.
A. has been completed B. have been completed
C. has completed D. have completed
高三英语单项填空中等难度题查看答案及解析
The construction of the two new railway lines ________ by now.
A.have been completed | B.has been completed |
C.has completed | D.have completed |
高三英语单项填空中等难度题查看答案及解析
With the virus spreading throughout the world, worldwide major media have been_______with the reports related to how to handle the situation.
A.occupied B.infected C.consumed D.littered
高三英语单项填空困难题查看答案及解析
WASHINGTON—Two-thirds of the world’s polar bear population could be gone by 2050 if predictions of melting sea ice hold true, the US Geological Survey reported on Friday.
The fate of polar bears could be even worse than that estimate, because sea ice in the Arctic might be disappearing faster than the available computer models predict, the geological survey said in a report aimed at determining whether the big white bear should be listed as a threatened species.
“There is a definite link between changes in the sea ice and the welfare of polar bears,” said Steve Amstrup, who led the research team. He says Arctic sea ice is already at the lowest this year and is expected to retreat(退却) farther this month.
That means that polar bears—some 16,000 of them -- will disappear by 2050 from parts of the Arctic where sea ice is melting most rapidly, along the north coasts of Alaska and Russia, researchers said in a telephone briefing(简报).
Other polar bears could survive beyond that date but many of those could be gone by 2100, Amstrup said. By this century’s end, the only polar bears left might live in the Canadian Arctic islands and along the west coast of Greenland.
“It is likely to result in loss of approximately two-thirds of the world’s current polar bear population by the mid 21st century,” the report’s executive summary said.
“Because the observed trajectory(轨迹)of Arctic sea ice decline appears to be underestimated by currently available models, this assessment of future polar bear status may be conservative(保守的).”
In January, the US Fish and Wildlife Service proposed listing the polar bear as a threatened species, noting polar bears depend on sea ice as a platform to hunt seals, their main food.
Without enough sea ice, polar bears would be forced onto land, but they are poor hunters once they get out of the water and ice, the researchers said. The bears’ disappearance would probably take place as young cubs(幼兽)failed to survive to adulthood and females were unable to reproduce successfully.
1.What was the US Geological Survey intended to do?
A.To determine whether the polar bear was in danger.
B.To measure how fast the sea ice melts in the Arctic.
C.To check the predictions of the computer models.
D.To find out the exact number of the polar bear.
2.What causes the polar bears to disappear by 2050?
A.The pollution of the Arctic region. B.The sea ice melting at high speed
C.Fewer food sources being left. D.The temperature getting colder.
3.The key to preventing polar bears dying out seems to _______________.
A.help young polar bears to survive the cold winter
B.have large number of seals living in the oceans
C.make sure there is enough sea ice in the Arctic
D.provide chances for adult polar bears to reproduce
高三英语阅读理解中等难度题查看答案及解析
Time flies! This is _1. third year that I have been in this school. In the past two and a half years, our school 2. __ (organize) many activities. What impressed me __3. __ (much) was an activity 4. __ (call) “Learning to Farm”. On an autumn afternoon, we _5. _ (send) to a farm6. ___ we learnt to plant potatoes. __7. _ (be) in the city for such a long time, we were so happy to go to the countryside. After 8. __ (divide) into three groups, we started to work. Some cut potatoes 9. _ pieces, and_10. ___put the pieces of potatoes into the holes and put the earth back.
高三英语语法填空中等难度题查看答案及解析