单选集
单选集
B We’ve considered several ways of paying to cut inline: hiring line standers, buying tickets from scalpers (票贩子), or purchasing line cutting privileges directly from, say, an airline or an amusement park. Each of these deals replaces the morals of the queue (waiting your turn) with the morals of the market (paying a price for faster service). Markets and queues—paying and waiting—are two different ways of allocating things, and each is appropriate to different activities. The morals of the queue, “First come, first served,”have an egalitarian(平等主义的) appeal. They tell us to ignore privilege, power, and deep pockets. The principle seems right on play grounds and at bus stops. But the morals of the queue do not govern all occasions. If I put my house up for sale, I have no duty to accept the first offer that comes along, simply because it’s the first. Selling my house and waiting for a bus are different activities, properly governed by different standards. Sometimes standards change, and it is unclear which principle should apply. Think of the recorded message you hear, played over and over, as you wait on hold when calling your bank:“Your call will be answered in the order in which it was received.”This is essential for the morals of the queue. It’s as if th ecompany is trying to ease our impatience with fairness. But don’t take the recorded message too seriously. Today, some people’s calls are answered faster than others. Call center technology enables companies to“score”incoming call sand to give faster service to those that come from rich places. You might call this telephonic queue jumping. Of course, markets and queues are not the only ways of allocating things. Some goods we distribute by merit, others by need, still others by chance. However, the tendency of markets to replace queues, and other non-market ways of allocating goods is so common in modern life that we scarcely notice it anymore. It is striking that most of the paid queue-jumping schemes we’ve considered—at airports and amusement parks, in call centers, doctors’offices, and national parks—are recent developments, scarcely imaginable three decades ago. The disappearance of the queues in these places may seem an unusual concern, but these are not the only places that markets have entered.The example of the recorded message in Paragraphs 4 and 5 illustrates.
A:the necessity of patience in queuing B:the advantage of modern technology C:the uncertainty of allocation principle D:the fairness of telephonic services
Passage Four
Archimedes was a famous Greek mathematician and scientist. He was born around 287 BC and he died in the year 212 BC.
Archimedes is most well-known for one specific idea that he came up with. "Archimede’s Principle" states that a solid object which is immersed in a liquid is pushed up by a force which is equal to the weight of the water that the object moves. For example, if you put a piece of wood and a piece of gold the same size in water, only the wood will float. Both the wood and gold move the same amount of water, but the wood weighs less than this water, while the gold weighs more.
It is believed that Archimedes discovered this principle when the king of Syracuse asked him to solve a problem. The king wanted to know if his crown was pure gold or a mixture of gold and silver. The king, of course, did not melt his crown to find out. The idea came to Archimedes as he lowered himself into his bath. He noticed how the water spilled out of the tub. He decided to use the same idea for the crown. He knew that a gold crown immersed in water would weigh more than one made of silver. The experiment was done and the goldsmith was proved guilty of trying to cheat the king.
A:Archimedes B:Archimedes’Principle C:A gold and silver crown D:The king of Syracuse
Archimedes was a famous Greek mathematician and scientist. He was born around 287 BC and he died in the year 212 BC.
Archimedes is most well-known for one specific idea that he came up with. "Archimedes’s Principle" states that a solid object which is immersed in a liquid is pushed up by a force which is equal to the weight of the water that the object moves. For example, if you put a piece of wood and a piece of gold the same size in water, only the wood will float. Both the wood and gold move the same amount of water, but the wood weighs less than this water, while the gold weighs more.
It is believed that Archimedes discovered this principle when the king of Syracuse asked him to solve a problem. The king wanted to know if his crown was pure gold or a mixture of gold and silver. The king, of course, did not melt his crown to find out. The idea came to Archimedes as he lowered himself into his bath. He noticed how the water spilled out of the tub. He decided to use the same idea for the crown. He knew that a gold crown immersed in water would weigh more than one made of silver. The experiment was done and the goldsmith was proved guilty of trying to cheat the king.
A good title for the selection is______.
A:Archimedes B:Archimedes’s Principle C:A Gold and Silver Crown D:The King of Syracuse
Passage Four
Archimedes was a famous Greek mathematician and scientist. He was born around 287 BC and he died in the year 212 BC.
Archimedes is most well-known for one specific idea that he came up with. "Archimede’s Principle" states that a solid object which is immersed in a liquid is pushed up by a force which is equal to the weight of the water that the object moves. For example, if you put a piece of wood and a piece of gold the same size in water, only the wood will float. Both the wood and gold move the same amount of water, but the wood weighs less than this water, while the gold weighs more.
It is believed that Archimedes discovered this principle when the king of Syracuse asked him to solve a problem. The king wanted to know if his crown was pure gold or a mixture of gold and silver. The king, of course, did not melt his crown to find out. The idea came to Archimedes as he lowered himself into his bath. He noticed how the water spilled out of the tub. He decided to use the same idea for the crown. He knew that a gold crown immersed in water would weigh more than one made of silver. The experiment was done and the goldsmith was proved guilty of trying to cheat the king.
A:Archimedes B:Archimedes' Principle C:A gold and silver crown D:The king of Syracuse
Archimedes was a famous Greek mathematician and scientist. He was born around 287 BC and he died in the year 212 BC.
Archimedes is most well-known for one specific idea that he came up with. "Archimedes’s Principle" states that a solid object which is immersed in a liquid is pushed up by a force which is equal to the weight of the water that the object moves. For example, if you put a piece of wood and a piece of gold the same size in water, only the wood will float. Both the wood and gold move the same amount of water, but the wood weighs less than this water, while the gold weighs more.
It is believed that Archimedes discovered this principle when the king of Syracuse asked him to solve a problem. The king wanted to know if his crown was pure gold or a mixture of gold and silver. The king, of course, did not melt his crown to find out. The idea came to Archimedes as he lowered himself into his bath. He noticed how the water spilled out of the tub. He decided to use the same idea for the crown. He knew that a gold crown immersed in water would weigh more than one made of silver. The experiment was done and the goldsmith was proved guilty of trying to cheat the king.
A good title for the selection is______.
A:Archimedes B:Archimedes’s Principle C:A Gold and Silver Crown D:The King of Syracuse
Archimedes was a famous Greek mathematician and scientist. He was born around 287 BC and he died in the year 212 BC.
Archimedes is most well-known for one specific idea that he came up with. "Archimedes’s Principle" states that a solid object which is immersed in a liquid is pushed up by a force which is equal to the weight of the water that the object moves. For example, if you put a piece of wood and a piece of gold the same size in water, only the wood will float. Both the wood and gold move the same amount of water, but the wood weighs less than this water, while the gold weighs more.
It is believed that Archimedes discovered this principle when the king of Syracuse asked him to solve a problem. The king wanted to know if his crown was pure gold or a mixture of gold and silver. The king, of course, did not melt his crown to find out. The idea came to Archimedes as he lowered himself into his bath. He noticed how the water spilled out of the tub. He decided to use the same idea for the crown. He knew that a gold crown immersed in water would weigh more than one made of silver. The experiment was done and the goldsmith was proved guilty of trying to cheat the king.
A:Archimedes B:Archimedes’s Principle C:A Gold and Silver Crown D:The King of Syracuse
{{B}}第二篇{{/B}}
| ? ?The use of heat pumps has been held
back largely by skepticism about advertisers’ claims that heat pumps can provide
as many as two units of thermal energy for each unit of electrical energy used,
thus apparently contradicting the principle of energy conservation. ? ?Heat pumps circulate a fluid refrigerant(致冷剂) that cycles alternatively from its liquid phase to its vapor phase in a closed loop. The refrigerant, starting as a low-temperature, lowpressure vapor, enters a compressor ’driven by an electric motor. The refrigerant leaves the compressor as a hot, dense vapor and flows through a heat exchanger called the condenser, which transfers heat from the refrigerant to a body of air. Now the refrigerant, as a high-pressure, ?cooled liquid confronts a flow restriction which causes the pressure to drop. As the pres sure falls, the refrigerant expands and partially vaporizes, becoming chilled. It then passes through a second heat exchanger, the evaporator, which transfers heat from the air to the refrigerant, reducing the temperature o{ this second body of air. Of the two heat exchangers, one is located inside, and the other one outside the house, so each is in contact with a different body of air: room air and outside air, respectively. ? ?The flow direction of refrigerant through a heat pump is controlled by valves. When the refrigerant flow is reversed, the heat exchangers switch function. This flow-reversal capability allows heat exchangers switch function. This flow-reversal capability allows heat pumps either to heat or cool room air. ? ?Now, if under certain conditions a heat pump puts out more thermal energy than it consumes in electrical energy, has the law of energy conservation been challenged? No, not even remotely: the additional input of thermal energy into the circulating refrigerant via the evaporator accounts for the difference in the energy equation. ? ?Unfortunately, there is one real problem. The heating capacity of a heat pump decreases as the outdoor temperature falls. The drop in capacity is caused by the lessening amount of refrigerant mass moved through the compressor at one time. The heating capacity is proportional to this mass flow rate: the less the mass of refrigerant being compressed, the less the thermal load it can transfer through the heat-pump cycle. The volume {low rate of refrigerant vapor through the single-speed rotary compressor used in heat pumps is approximately constant. But cold refrigerant vapor entering a compressor is at lower pressure than warmer vapor. Therefore, the mass of cold refrigerant—and thus the thermal energy it carries—is less than ii the refrigerant vapor were warmer before compression. ? ?Here, then, lies a genuine drawback of heat pumps: in extremely cold climates—where the most heat is needed—heat pumps are least able to supply enough heat. |
A:carefully qualifying the meaning o{ that principle B:pointing out a factual error in the statement that gives rise to this question C:supplying additional relevant facts D:denying the relevance of that principle to heat pumps.
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