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单选题
The water of the Great Salt Lake is _____ seawater.
A
saltier than that of
B
as salty as that of
C
saltier than
D
so salty as
参考答案
参考解析
解析：
本题考查形容词。句意：大盐湖的水比海水还要咸。在原级结构“as ... as ...”和比较级结构中，要注意前后比较的对象要对等。
本题考查形容词。句意：大盐湖的水比海水还要咸。在原级结构“as ... as ...”和比较级结构中，要注意前后比较的对象要对等。
更多 “单选题The water of the Great Salt Lake is _____ seawater.A saltier than that ofB as salty as that ofC saltier thanD so salty as” 相关考题
考题
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
考题
The water in an auxiliary boiler should be tested for chloride content to determine ( ).A.total dissolved solidsB.salt contaminationC.water harcnessD.chlorine contamination
考题
请阅读短文，完成此题。
When we analyze the salt salinity(盐溶度 ) of ocean waters, we find that it varies only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation. In this manner, the salinity is increased, since the salt stays behind. If this is carried to the extreme, of course, white salt would be left behind; this, by the way, is how much of the table salt we use is actually obtained.
The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of
high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by-evaporation, or decreased by the addition of fresh water by precipitation.
Normally, in hot regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas.
A third process by which salinity may be altered is associated with the formation and melting of sea ice. When seawater is frozen, the dissolved materials are left behind. In this manner, seawater directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water.
In the Weddell Sea, the densest water in the ocean is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portion of the oceans of the world.
Which of the following statements is TRUE according to the passage?
查看材料
A．Oceanic salinity has great effect on sea life.
B．Many factors combine to cause changes in oceanic salinity.
C．The movement of the water is related to the amount of salt.
D．The temperature of the water has much to do with the oceanic salinity.
考题
共用题干
Where Has the Salt Come from?Every now and then,we meet a fact about our earth that makes us feel strange and no answer for the fact has yet been found.Such a fact is the existence of salt in the oceans. How did it get there?We simply do not know how the salt got into the ocean!We do know,of course,that salt is water-soluble,and so passes into the oceans with rainwater.The salt of the earth's surface is constantly being dissolved（溶解）and is passing into the ocean.But we do not know whether this can explain the huge quantity of salt in oceans.If all the oceans were dried up,enough salt would be left to build a wall 180 miles high and a mile thick. Such a wall would reach once around the world at the Equator（赤道）!The common salt that we all use is produced from seawater or the water of salt lakes, from salt springs（源泉）and from deposits of rock salt. The concentration（浓度）of salt in seawater ranges from about three percent to three-and-one-half percent. The Dead Sea, which covers an area of about 340 square miles,contains about 11,600,000,000 tons of salt!On the average, a gallon（加仑）of seawater contains about a quarter of a pound of salt.The beds of rock salt that are found in various parts of the world were all originally formed by the evaporation（蒸发）of seawater millions of years ago. It is believed that the thick rock-salt deposits were formed after about nine-tenth of theY volume of seawater had been evaporated.Most commercial salt is obtained from rock salt.The usual method is to drill wells（井） down to the salt beds. Pure water is pumped down（抽进去）through a pipe. The water dissolves the salt and it is forced through another pipe up to the surface.A:Right B:Wrong C:Not mentioned
考题
共用题干
Where Has the Salt Come from?Every now and then,we meet a fact about our earth that makes us feel strange and no answer for the fact has yet been found.Such a fact is the existence of salt in the oceans. How did it get there?We simply do not know how the salt got into the ocean!We do know,of course,that salt is water-soluble,and so passes into the oceans with rainwater.The salt of the earth's surface is constantly being dissolved（溶解）and is passing into the ocean.But we do not know whether this can explain the huge quantity of salt in oceans.If all the oceans were dried up,enough salt would be left to build a wall 180 miles high and a mile thick. Such a wall would reach once around the world at the Equator（赤道）!The common salt that we all use is produced from seawater or the water of salt lakes, from salt springs（源泉）and from deposits of rock salt. The concentration（浓度）of salt in seawater ranges from about three percent to three-and-one-half percent. The Dead Sea, which covers an area of about 340 square miles,contains about 11,600,000,000 tons of salt!On the average, a gallon（加仑）of seawater contains about a quarter of a pound of salt.The beds of rock salt that are found in various parts of the world were all originally formed by the evaporation（蒸发）of seawater millions of years ago. It is believed that the thick rock-salt deposits were formed after about nine-tenth of theY volume of seawater had been evaporated.Most commercial salt is obtained from rock salt.The usual method is to drill wells（井） down to the salt beds. Pure water is pumped down（抽进去）through a pipe. The water dissolves the salt and it is forced through another pipe up to the surface.Beds of rock salt are found in every part of the world.A:Right B:Wrong C:Not mentioned
考题
共用题干
Where Has the Salt Come from?Every now and then,we meet a fact about our earth that makes us feel strange and no answer for the fact has yet been found.Such a fact is the existence of salt in the oceans. How did it get there?We simply do not know how the salt got into the ocean!We do know,of course,that salt is water-soluble,and so passes into the oceans with rainwater.The salt of the earth's surface is constantly being dissolved（溶解）and is passing into the ocean.But we do not know whether this can explain the huge quantity of salt in oceans.If all the oceans were dried up,enough salt would be left to build a wall 180 miles high and a mile thick. Such a wall would reach once around the world at the Equator（赤道）!The common salt that we all use is produced from seawater or the water of salt lakes, from salt springs（源泉）and from deposits of rock salt. The concentration（浓度）of salt in seawater ranges from about three percent to three-and-one-half percent. The Dead Sea, which covers an area of about 340 square miles,contains about 11,600,000,000 tons of salt!On the average, a gallon（加仑）of seawater contains about a quarter of a pound of salt.The beds of rock salt that are found in various parts of the world were all originally formed by the evaporation（蒸发）of seawater millions of years ago. It is believed that the thick rock-salt deposits were formed after about nine-tenth of theY volume of seawater had been evaporated.Most commercial salt is obtained from rock salt.The usual method is to drill wells（井） down to the salt beds. Pure water is pumped down（抽进去）through a pipe. The water dissolves the salt and it is forced through another pipe up to the surface.The author is sure that the dissolved salt from the earth's surface is the only source of the huge quantity of salt found in oceans.A:Right B:Wrong C:Not mentioned
考题
共用题干
Where Has the Salt Come from?Every now and then,we meet a fact about our earth that makes us feel strange and no answer for the fact has yet been found.Such a fact is the existence of salt in the oceans. How did it get there?We simply do not know how the salt got into the ocean!We do know,of course,that salt is water-soluble,and so passes into the oceans with rainwater.The salt of the earth's surface is constantly being dissolved（溶解）and is passing into the ocean.But we do not know whether this can explain the huge quantity of salt in oceans.If all the oceans were dried up,enough salt would be left to build a wall 180 miles high and a mile thick. Such a wall would reach once around the world at the Equator（赤道）!The common salt that we all use is produced from seawater or the water of salt lakes, from salt springs（源泉）and from deposits of rock salt. The concentration（浓度）of salt in seawater ranges from about three percent to three-and-one-half percent. The Dead Sea, which covers an area of about 340 square miles,contains about 11,600,000,000 tons of salt!On the average, a gallon（加仑）of seawater contains about a quarter of a pound of salt.The beds of rock salt that are found in various parts of the world were all originally formed by the evaporation（蒸发）of seawater millions of years ago. It is believed that the thick rock-salt deposits were formed after about nine-tenth of theY volume of seawater had been evaporated.Most commercial salt is obtained from rock salt.The usual method is to drill wells（井） down to the salt beds. Pure water is pumped down（抽进去）through a pipe. The water dissolves the salt and it is forced through another pipe up to the surface.If all the oceans were dried up,the salt thus obtained would be extremely great in size.A:Right B:Wrong C:Not mentioned
考题
The largest lake in Britain is( ). A.the Lake Neagh
B.Windermere Water
C.Coniston Water
D.the Lake District
考题
单选题Since 1960, the fast-growing town of Hotstone, Arizona, has drawn water from the Gray River, which feeds Lake Mudfish. If the town’s water use continues to grow at its present rate, in about 20 years the water level of Lake Mudfish will inevitably decrease to the point that it can no longer support its biologically fragile population of fish. The prediction above is based on which of the following assumptions?A
As the town’s water requirements grow, it will not be able to meet those requirements by drawing on water sources other than the Gray River.B
Since 1960, the lake’s population of fish has become more biologically fragile.C
The amount of water that the lake loses to evaporation each year will increase over the next two decades.D
There are multiple sources of water besides the Gray River that feed into Lake Mudfish.E
The town of Hotstone will be able to reverse its trend of increasing water use if it implements an aggressive water conservation program.
考题
单选题Passage2 Questions 6 to 10 are based on the following passage. Salt is as necessary to life as water. In many areas of Africa people once drank the urine（尿）of animals because they had no other source of salt. Without salt, human beings die. The human body demands that the amount of salt in the blood always stay the same. When the body does not get enough salt, it protects itself by letting less salt leave the body in. urine and sweat. But it cannot reduce this output to zero. Some salt is always escaping. On a completely saltless diet, like that of some people in Africa, the body steadily loses small amounts of salt through the kidneys（肾） and sweat glands(腺). It then tries to adjust to this loss by speeding up its secretion(分泌) of water. (78) In this way, the body attempts to keep the amount of salt in the blood at the necessary level. The result is a slow drying up of body and, finally, death. The person dies of thirst. In cases where there is little or no water to drink, the body tries to do the opposite thing.Again, it must keep the salt level in the blood constant. Because it has little water, it attempts to stop water from leaving the body and to increase its secretion of. salt. But, as with the escaping salt, it cannot be completely successful. Some water still leaves and the person eventually dies of thirst. In short, the body's normal needs for salt and for water are both parts of the same important need to keep the salt level in the blood constant.6 Some African people once drank animal urine______.A
when they were going to dieB
because they were thirstyC
because there was little saltD
because they were short of water
考题
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 is the function of the chillers in a traditional air-conditioning system?A
They pump the air continuously to the units in each room.B
They lower the temperature of the water in the system.C
They help the water cool down naturally on the roof .D
They gradually clean the water as it flows through the building.
考题
单选题Passage2 Questions 6 to 10 are based on the following passage. Salt is as necessary to life as water. In many areas of Africa people once drank the urine（尿）of animals because they had no other source of salt. Without salt, human beings die. The human body demands that the amount of salt in the blood always stay the same. When the body does not get enough salt, it protects itself by letting less salt leave the body in. urine and sweat. But it cannot reduce this output to zero. Some salt is always escaping. On a completely saltless diet, like that of some people in Africa, the body steadily loses small amounts of salt through the kidneys（肾） and sweat glands(腺). It then tries to adjust to this loss by speeding up its secretion(分泌) of water. (78) In this way, the body attempts to keep the amount of salt in the blood at the necessary level. The result is a slow drying up of body and, finally, death. The person dies of thirst. In cases where there is little or no water to drink, the body tries to do the opposite thing.Again, it must keep the salt level in the blood constant. Because it has little water, it attempts to stop water from leaving the body and to increase its secretion of. salt. But, as with the escaping salt, it cannot be completely successful. Some water still leaves and the person eventually dies of thirst. In short, the body's normal needs for salt and for water are both parts of the same important need to keep the salt level in the blood constant.10 What is the main idea of the passage?A
Salt is very important.B
If their blood salt level is not constant, human beings may die.C
The amount of salt in the body is secreted.D
People can die of thirst.
考题
单选题If you swim in a river or lake, be sure to investigate________is below the water surface. Often there are rocks or branches hidden in the water.A
whatB
whoC
thatD
whoever
考题
单选题What does salt water draft mean?（）.A
It means summer draftB
It means maximum draftC
It means fresh water draftD
It means seawater draft
考题
单选题A salinity indicator is used to determine the （）.A
cause of salt contaminationB
location of salt water contaminationC
chemical makeup of feed-waterD
level of alkalinity in condensate
考题
单选题（） is used for cylinder and cylinder head, the salt water is used for cooling the lubricating oil, the fresh water in the coolers and the charging air in the air cooler.A
The fuel oilB
The lube oilC
The sea waterD
The fresh water
考题
单选题Passage2 Questions 6 to 10 are based on the following passage. Salt is as necessary to life as water. In many areas of Africa people once drank the urine（尿）of animals because they had no other source of salt. Without salt, human beings die. The human body demands that the amount of salt in the blood always stay the same. When the body does not get enough salt, it protects itself by letting less salt leave the body in. urine and sweat. But it cannot reduce this output to zero. Some salt is always escaping. On a completely saltless diet, like that of some people in Africa, the body steadily loses small amounts of salt through the kidneys（肾） and sweat glands(腺). It then tries to adjust to this loss by speeding up its secretion(分泌) of water. (78) In this way, the body attempts to keep the amount of salt in the blood at the necessary level. The result is a slow drying up of body and, finally, death. The person dies of thirst. In cases where there is little or no water to drink, the body tries to do the opposite thing.Again, it must keep the salt level in the blood constant. Because it has little water, it attempts to stop water from leaving the body and to increase its secretion of. salt. But, as with the escaping salt, it cannot be completely successful. Some water still leaves and the person eventually dies of thirst. In short, the body's normal needs for salt and for water are both parts of the same important need to keep the salt level in the blood constant.7 In order to adjust to the loss of salt, the body______.A
loses some bloodB
speeds up its secretion of waterC
speeds up its secretion of saltD
is drying up slowly
考题
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?A
It is used by the residents of Toronto.B
It is returned to a place deep in the lake.C
It is cooled down before being used again.D
It is added to the water inside air-conditioning systems.
考题
单选题In motorships，there are two main circuits, （）.A
one salt water, one fresh waterB
one salt water, one fuelC
one fresh water, one fuelD
one steam, one fuel
考题
单选题How did the immigrants in Salt Lake City feel about “Operation Safe Travel”?A
Guilty.B
Offended.C
Disappointed.D
Discouraged.
考题
单选题（）provides strength and strong space for fule,lubricating oil,fresh water,salt(ballast)water and potable water.A
The double bottomB
The cofferdamC
The navigating bridgeD
The superstructure
考题
单选题Passage2 Questions 6 to 10 are based on the following passage. Salt is as necessary to life as water. In many areas of Africa people once drank the urine（尿）of animals because they had no other source of salt. Without salt, human beings die. The human body demands that the amount of salt in the blood always stay the same. When the body does not get enough salt, it protects itself by letting less salt leave the body in. urine and sweat. But it cannot reduce this output to zero. Some salt is always escaping. On a completely saltless diet, like that of some people in Africa, the body steadily loses small amounts of salt through the kidneys（肾） and sweat glands(腺). It then tries to adjust to this loss by speeding up its secretion(分泌) of water. (78) In this way, the body attempts to keep the amount of salt in the blood at the necessary level. The result is a slow drying up of body and, finally, death. The person dies of thirst. In cases where there is little or no water to drink, the body tries to do the opposite thing.Again, it must keep the salt level in the blood constant. Because it has little water, it attempts to stop water from leaving the body and to increase its secretion of. salt. But, as with the escaping salt, it cannot be completely successful. Some water still leaves and the person eventually dies of thirst. In short, the body's normal needs for salt and for water are both parts of the same important need to keep the salt level in the blood constant.8 Which of the following statements is NOT the result of a lack of salt in the body?A
The body secretes more water.B
The body dries up.C
The person dies of thirst.D
The person gets fatter.
考题
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.Which of the following is true?A
Enwave's system is said to work only in cities located near the Great Lakes.B
The water deep in Lake Ontario always remains at the same temperature.C
Experts warn that the use of CFCs in Enwave' s system will add to global warming.D
Toronto is now searching for new natural sources of water to use in its water supply.
考题
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 is one problem with traditional air-conditioning systems?A
The chemicals they use sometimes pollute the water supply.B
They often damage the buildings that they are trying to cool.C
There are not enough CFCs in the world to cool all the buildings.D
The method they use to cool water is thought to harm the ozone layer.
考题
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 is one advantage of Enwave 's new system?A
It keeps buildings much cooler than other methods.B
It can be used by large cities anywhere in the world.C
It is much more energy-efficient than traditional systems.D
It keeps water from being used for more than one purpose.
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