--Why does the Lake smell terrible?--Because large quantities of water .A. have polluted B. is being polluted C. has been polluted D. have been polluted
--Why does the Lake smell terrible?
--Because large quantities of water .
A. have polluted B. is being polluted C. has been polluted D. have been polluted
相关考题：
—Why does the stream smell terrible? —Because large quantities of water_____. A、have pollutedB、is being pollutedC、has been pollutedD、have been polluted
Why does the author think the BMGF is the most innovative and successful in history? _________.A． Because their money is ruled to be given to the really needy people.B． Because they insist that good intentions should lead to good results.C． Because their response is immediate if the need is immediate.D． Because they have to know that every check from Seattle is actually used.
Wild dogs are dangerous predators because they ______.A. are very fierceB. hunt in large packsC. are very intelligentD. have unusually large litters
BThe world is not only hungry，it is also thirsty for water． this may seem strange to you，since nearly 75% of the earth is covered with water． But about 97% of this water is sea water．Man can only drink and use the other 3% fresh water that comes from rivers，lakes，under-ground and other places． And we cannot even use all of that，because some of this fresh water has been made dirty．At the moment，this small amount(数量) of fresh water is still enough for us． However，our need for water is getting greater and greater． Only if we take steps to solve this problem now，we can get away from a serious world water shortage later on． The people of the world cannot have an enjoyable life without enough clean water．On one hand we should stop wasting this little water of ours，on the other hand we should find ways to reuse it，but this has not been done widely．Today，in most large cities，water is used only once and it then returns to the sea or runs into underground places．lf we can make it clean again，it can be used once more just as if it were fresh from a spring．But even if large cities reuse its water，we still would not have enough in the future． Where．could we turn to next for water? To the ocean! How can we do to make use of this great a-mount of sea water? We can take the salt from the water to make it fresh．So if we take all these steps，we'll be in no danger of drying up!( )26． Why does the writer say that the world is thirsty for water?A． The amount of fresh water is really very small．B． The people of the world waste too much water．C． The people of the world have to drink a lot of water every day．D． There are too many people in the world needing water．
Passage ThreeA group of scientists rowing toward the center of a lake saw something shocking. They turned back as fast as they could. What had they seen.? The lake was boiling!The group was investigating a crater lake in the mountains of St. Vincent. A crater lake is the mouth of a volcano that has been dormant for some time and has filled with water.This particular crater was the tip of a volcano called Soufriere, which erupted last in 1902. Since that time, it had not shown any signs of action. But in the fall of 1971, mountain climbers who had hiked near the lake returned to the lowlands with strange stories. They said the water had turned yellow and was giving off a smell like burnt eggs. A seething fog was rising from the lake's surface.Local scientists rushed to Soufriere to see if this might be the beginning of a new volcanic explosion. They found a huge black mass in the middle of the water. It was a great blob 1,000 feet long and 300 feet wide. Lava had pushed up through the bottom of the lake and formed a new island.The investigators wanted to make sure that the volcano was safe, and that the lava would not over- flow into the surrounding countryside. But they could never reach the island to study it, because the lava was so hot that the water around it bubbled and boiled.44. This passage is about ______.A. mountain climbingB. a boiling lakeC. a new volcanic islandD. a mysterious blob
23． Why does Philip like action movies?A． Because they are scary．B． Because they are interesting．C． Because they are exciting．D． Because they are boring，
Passage FiveThe Northern Pike is a very bad fish. It is a big, hungry fish, and swallows little fish such as trout and perch. Many Northern Pikes live in Lake Davis. They are killing all the smaller fish in the lake. The Northern Pike are a serious threat to the lake because they eat all the smaller fish. Soon, all other species of fish in the lake will be killed off. This is not healthy for the environment.Experts are afraid that the Northern Pike will swim out of Lake Davis through many smaller rivers that feed into the lake. They could spread all over the country and damage many other water environments. If that happens, it would be too late to stop the Northern Pike.For ten years, officials have been trying to remove the Northern Pike from Lake Davis. They haw. tried using nets, explosives and poisons. However, the Northern Pike population is still doing well in Lake Davis. Many people do not like the idea of using poison to kill the fish. They worry that the poi- sons are bad for humans who use the water. No trace of the poisons has ever been found in local wells, however.Scientists are going to try the poison again. This time, they will drain the lake before they add the poison to the water. A public hearing will be held to talk about the problem.52. Why are some people against the use of poisons to kill Northern Pike?A. Fishermen will be poisoned too.B. The poisons are expensive.C. They think that wells will be polluted.D. The lake will become unsafe.
What a waste! Why do you () the water () all the time ? A、have…flowingB、have…flowC、have…to flowD、have…flowed
27． Why does eating apples make one-s stomach want less food?A． Because apples are delicious．B． Because apples are full of fiber and water．C． Because apples are sour．D． Because only apples are filled with calories．
Persons who have swallowed a non-petroleum based poison are given large quantities of warm soapy water or warm salt water to ______.A.induce vomitingB.absorb the poison from the bloodC.neutralize the poison in the bloodD.increase the digestive process and eliminate the poison
Why do American restaurants serve large portions?A Because Americans associate quantity with value.B Because Americans have big bellies.C Because Americans are good eaters.D Because Americans are greedy.
Why did the driver stop his car suddenly and jump out of it? __________A.Because he supposed something must have gone wrong with his carB.Because he was moved by the pretty voice of Mrs．JanesC.Because he wondered what had happened to Mrs．JanesD.Because he was frightened by the terrible voice of Mrs．Janes
共用题干The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water, birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them, lakes may mean terrible disasters.In 1984,poisonous gases exploded out of Lake Monoun and came down into the nearby villages,killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes.They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However, poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake.In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottom than other crater lakes.In fact, scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster.Now scientists from the United States,France,and Cameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.They stood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air.Near the top of the pipe,the team put several holes that could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level,computers will set off loud sirens（警 报）and bright lights to warn the people in the villages.In that way,they will have time to escape from the dangerous gases.Which of the following statements about Lake Nyos and Lake Monoun is true?A:They were formed in 1984.B:They are at the top of two active volcanoes.C:They are not like most other crater lakes.D:Water in them turns over regularly.
共用题干第三篇The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water,birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them,lakes may mean terrible disasters.In 1984, poisonous gases exploded out of Lake Monoun and came down into the nearby villages, killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes. They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However,poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake. In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottomthan other crater lakes.In fact,scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster. Now scientists from the United States,France,andCameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.Theystood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air. Near the top of the pipe,the team put several holesthat could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level, computers will set off loud sirens（警报）and bright lights to warn the people in the villages. That way,they will have time to escape from the dangerous gases.A team of scientists hasA:erected a pressure-releasing pipe in the lake.B:identified the gases at the bottom of the lake.C:built a beautiful fountain near the lakes.D:removed all dangerous gases from the lakes.
共用题干The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water, birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them, lakes may mean terrible disasters.In 1984,poisonous gases exploded out of Lake Monoun and came down into the nearby villages,killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes.They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However, poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake.In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottom than other crater lakes.In fact, scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster.Now scientists from the United States,France,and Cameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.They stood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air.Near the top of the pipe,the team put several holes that could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level,computers will set off loud sirens（警 报）and bright lights to warn the people in the villages.In that way,they will have time to escape from the dangerous gases.Lake Nyos and Lake Monoun explode because_____.A:the gases rise to the top and mix with airB:people from the villages turn over the waterC:scientists have put in a computer systemD:they have more gases trapped at the bottom than other crater lakes
共用题干第三篇The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water,birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them,lakes may mean terrible disasters.In 1984, poisonous gases exploded out of Lake Monoun and came down into the nearby villages, killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes. They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However,poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake. In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottomthan other crater lakes.In fact,scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster. Now scientists from the United States,France,andCameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.Theystood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air. Near the top of the pipe,the team put several holesthat could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level, computers will set off loud sirens（警报）and bright lights to warn the people in the villages. That way,they will have time to escape from the dangerous gases.Lake Nyos and Lake Monoun explode becauseA:the gases rise to the top and mix with air.B:people from the villages turn over the water.C:scientists have put in a computer system.D:they have more gases trapped at the bottom than other crater lakes.
共用题干The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water, birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them, lakes may mean terrible disasters.In 1984,poisonous gases exploded out of Lake Monoun and came down into the nearby villages,killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes.They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However, poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake.In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottom than other crater lakes.In fact, scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster.Now scientists from the United States,France,and Cameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.They stood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air.Near the top of the pipe,the team put several holes that could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level,computers will set off loud sirens（警 报）and bright lights to warn the people in the villages.In that way,they will have time to escape from the dangerous gases.What do we learn from the last paragraph?A:Scientists are planning to install pipes in all crater lakes.B:Scientists still do not know how to prevent gas explosions.C:Explosion disasters could be avoided in the future.D:Warning systems have been set up in the villages nearby.
共用题干The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water, birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them, lakes may mean terrible disasters.In 1984,poisonous gases exploded out of Lake Monoun and came down into the nearby villages,killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes.They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However, poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake.In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottom than other crater lakes.In fact, scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster.Now scientists from the United States,France,and Cameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.They stood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air.Near the top of the pipe,the team put several holes that could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level,computers will set off loud sirens（警 报）and bright lights to warn the people in the villages.In that way,they will have time to escape from the dangerous gases.A team of scientists has______.A:erected a pressure-releasing pipe in the lakeB:identified the gases at the bottom of the lakeC:built a beautiful fountain near the lakesD:removed all dangerous gases from the lakes
Deep inside a mountain near Sweetwater in East Tennessee is a bady?of water known as the Lost?Sea.It is listed by the Guinness Book of World Records as the world′s largest underground lake.The Lost Sea is part of an extensive and historic cave system called Craighead Caverns.The caverns have been known and used since the days of the Cherokee Indian nation.The cave?expands into a series of huge rooms from a small opening on the side of the mountain.Approximately?one mile from the entrance,in a room called-The Council Room",many Indian artifacts have been?found.Some of the items discovered include pottery,arrowheads,weapons,and jewelry.For many years there were persistent rumors of a large underground lake somewhere in a cave,but it was not discovered until 1905.In that year,a thirteen-year-old boy named Ben Sands crawled through a small opening three hundred feet underground.:He found himself in a large cave half filled?with water.Today tourists visit the Lost Sea and ride far out onto it in glass-bottomed boats powered by electric motors.More than thirteen acres of water have been mapped out so far and still no end to the lake has been found.Even though teams of divers have tried to explore the Lost Sea,the full extentof it is still unknown.The Lost Sea is unique because it is__________.A.part of a historical cave systemB.the biggest underground lake in the worldC.listed in the Guinness Book of World RecordsD.the largest body of water in Tennessee
Many businesses ship their products by rail if they are shipping long distance because it can be（）to ship in large quantities by rail than by truck.A、more expensiveB、cheaperC、fasterD、safer
单选题Why the cooling water of the diesel engine should be treated? Because the（）ACooling water is alkalescenceBcooling water is acidityCcooling water has salinityDcooling water has impurity
单选题Large quantities of uncovered pig iron or billets should not be carried in the upper-tween decks because（）.Athis does not eliminate the risk of cargo shiftingBthis will increase the metacentric height of the shipCthis will decrease the gravity height of the shipDthis will reduce the rolling period of the ship
单选题Because the flow rate of supply water pump is too large, oily water separator does not work wellWhich of the following is not the reason?（）Athe monitoring equipment is out of orderBseparating effect becomes badCinner wall is contaminatedDseparating effect becomes bad and inner wall is contaminated
单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.What happens in the end to the water from Lake Ontario?AIt is used by the residents of Toronto.BIt is returned to a place deep in the lake.CIt is cooled down before being used again.DIt is added to the water inside air-conditioning systems.
单选题Persons who have swallowed a non-petroleum based poison are given large quantities of warm soapy water or warm salt water to （）Ainduce vomitingBabsorb the poison from the bloodCneutralize the poison in the bloodDincrease the digestive process and eliminate the poison