The ______ heat has dried up the pond.A.concentratedB.extensiveC.intenseD.intensive
The ______ heat has dried up the pond.
A.concentrated
B.extensive
C.intense
D.intensive
The ______ heat has dried up the pond.
A.concentrated
B.extensive
C.intense
D.intensive
第1题
The missile has a heat seeking device, ______ (这使它能肛到目标).
第2题
Not too much of the plant faces the direct drying sunlight, so the cactus can_________.
A.keep the water it has stored
B.absorb much sunlight
C.store much heat from the sun
D.keep the food it has made
第3题
What is true about the greenhouse effect according to the passage?
A.It has been a disastrous process with earth for centuries.
B.Greenhouse gases prevent sunlight from reaching the earth and the heat from radiating back.
C.The greenhouse effect would never allow life to form.
D.The more greenhouse gases are released, the warmer the atmosphere will be.
第4题
What is wrong with the womans current apartment?
A.It has turned into a dump.
B.It can"t provide heat continually.
C.The landlord is a mean person.
D.The owner doesn"t fix the steam generator.
第5题
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.
The primary purpose of the passage is to ______.
A.explain the differences in the working of a heat pump when the out-door temperature changes
B.contrast the heating and the cooling modes of heat pumps
C.describe heat pumps, their use, and {actors affecting their use
D.advocate the more widespread use of heat pumps
第6题
Some parts of most modern building, theatres and offices【C8】______classrooms -- are more than amply heated by people and lights and sometimes must be air-conditioned and【C9】______in winter. The technique of【C10】______heat and redistributing it is【C11】______“heat recovery”. A few modem buildings recover【C12】______, but the university's system is the first to recover heat【C13】______some buildings and reuse it in【C14】______. Along the way, Pitt has learned a great deal about some of its heat producers. The【C15】______a student studies, the more heat his body【C16】______. Male students emit more than【C17】______students, and the larger a student, the more heat he【C18】______. It is tempting to【C19】______that the hot test prospect for the Johnstown campus would be a【C20】______over weight male genius.
【C1】
A.though
B.no matter
C.however
D.in spite of
第7题
Why is it wrong to argue that carbon dioxide drives global warming?
A.Because the sun and the oceans produce much more heat.
B.Because carbon dioxide generates very little heat.
C.Because the air has a smaller heat capacity.
D.Because there are many factors driving global temperature.
第8题
M: Thank you. As you can see, little by little, Americans are turning to solar power, tapping the strength of the sun for energy.
W: Yeah, that's true. Sunlight has already been used for heating or cooling homes and office buildings in the sunny south.
M: Experts say all signs point to the birth of the solar energy industry. Right now, an increasing number of companies are selling solar collector panels to heat and cool homes or to heat water. The glass and metal panels each cost from $100 to more than $500, and the three or four-bedroom home usually requires a dozen or more. They look like sandwiches. They are usually placed in rooftops. Nobody knows how many have been sold, and in addition, many people have built their own units. It has been estimated that solar power equipment will be a $1.3 billion industry by 1995, and more than a million homes will use sunlight for heat, air conditioning or to generate electricity, both in the cities and in countryside.
W: Wow! That is really big business.
What do we learn about the use of solar energy in the U. S. ?
A.It is very well established.
B.It is relatively new.
C.It is found in one million homes.
D.It is being rapidly expanded.
第9题
There are approximately three quarters of a ton of termites (白蚁) for every person on Earth. It now turns out that these critters may be helping to alter the climate and affect man's life.
For years scientists have been saying that carbon dioxide sent into the atmosphere by the burning of fuels might lead to the rise in temperatures of the whole earth, owing to the greenhouse effect in which the gas prevents the escape of heat into outer space. Now an international team of researchers has discovered that termites generate more than twice the carbon dioxide that fuel burning does. And this production, which comes from the insects' eating and consuming of different kinds of vegetables and wood, has risen greatly. This is chiefly because man has cut so many trees in order to open more land and thus has provided large quantities of food for the insects in the form. of tiny pieces of wood.
The output from the burning of fuels is of greater concern, however, because it is continuing to rise steadily and so far no effective measures have been taken to reduce the amount of carbon elements in this way. Production by termites, on the other hand, is not likely to increase much more.
From the passage we know that" the greenhouse effect" is an effect in which ______ .
A.low temperatures are created by using a house
B.the house is made green in order to keep heat
C.heat is prevented from escaping outside
D.everything is kept green in a house
第10题
What is the purpose of this report?
A.To advertise a new model
B.To inform. of a job opening
C.To announce a product recall
D.To talk about a sale