网友您好， 请在下方输入框内输入要搜索的题目：
题目内容
（请给出正确答案）
单选题
The reason why the laser beam is very strong is that ______.
A
it is artificially illuminated
B
it is made up of a concentrated beam of light
C
it sends out heat in all directions
D
its heat is increased by the heat of the sun
参考答案
参考解析
解析：
事实细节题。由关键词why the laser beam is very strong定位第二段最后一句可知“能量被集中到一起而变得强大”。故答案为B项。
事实细节题。由关键词why the laser beam is very strong定位第二段最后一句可知“能量被集中到一起而变得强大”。故答案为B项。
更多 “单选题The reason why the laser beam is very strong is that ______.A it is artificially illuminatedB it is made up of a concentrated beam of lightC it sends out heat in all directionsD its heat is increased by the heat of the sun” 相关考题
考题
CSometimes, the simplest ideas are the best. For example, to absorb heat from the sun to heat water, you need large, flat, black surfaces. One way to do that is to build those surfaces specially, on the roofs of buildings. But why go to all that trouble when cities are full of black surfaces already, in the form. of asphalt (柏油) roads?Ten years ago, this thought came into the mind of Arian de Bondt, a Dutch engineer. He finally persuaded his boss to follow it up. The result is that their building is now heated in winter and cooled in summer by a system that relies on the surface of the road outside.The heat-collector is a system of connected water pipes. Most of them run from one side of the street to the other, just under the asphalt road. Some, however, dive deep into the ground.When the street surface gets hot in summer, water pumped through the pipes picks up this heat and takes it underground through one of the diving pipes. At a depth of 100 metres lies a natural aquifer (蓄水层) into which several heat exchangers (交换器) have been built. The hot water from the street runs through these exchangers, warming the ground-water, before returning to the surface through another pipe. The aquifer is thus used as a heat store.In winter, the working system is changed slightly. Water is pumped through the heat exchangers to pick up the heat stored during summer. This water goes into the building and is used to warm the place up. After performing that task, it is pumped under the asphalt and its remaining heat keeps the road free of snow and ice.64. Which of the following is true according to the first two paragraphs?A. Arian de Bondt got his idea from his boss.B. Large, flat, black surfaces need to be built in cities.C. The Dutch engineer's system has been widely used.D. Heat can also be collected from asphalt roads.
考题
For what purpose are the diving pipes used?A. To absorb heat from the sun.B. To store heat for future use.C. To turn solar energy into heat energy.D. To carry heat down below the surface.
考题
To get some idea of the amount of heat the sun ________(1), think about this. If you ________(2)collect all the heat that hits the earth in a two-week period, it would equal the amount of all the other known sources and reserves of energy: wood, coal, and oil. But even these sources of energy depend ________(3) the sun for their formation. For example, a tree ________ (4) certainly never grow and provide fuel in the form. of wood were it not for the sun. Because the sun is so important in the production of all forms of heating fuel, more and more time and money are being spent ________(5) ways to change power from the sun directly into a form. of heat.1.A、gives offB、turns offC、takes offD、sets off2.A、willB、couldC、mustD、shall3.A、ofB、inC、onD、to4.A、willB、mustC、shallD、would5.A、studyB、studiedC、studyingD、being studying
考题
A laser beam can be made narrow enough to () a single cell.
A.focus onB.pay attention toC.concentrate onD.lay stress on
考题
Spontaneous combustion is caused by ______．A.An outside heat source heating a substance until it ignitesB.Conduction of heat through a wall of material to the substanceC.Chemical action within a substanceD.All of the above
考题
共用题干
Heat Is Killer Extremely hot weather is common in many parts of the world.Although hot weather just makes most people feel hot,it can_______(51)serious medical problems-even death.Floods,storms,volcano eruptions and other natural______(52)kill thousands of people every year.So______(53) extreme heat.Experts say heat may be nature's deadliest killer, Recently,extreme heat was blamed ______(54)killing more than one hundred people in India.It is reported that the total heat of a hot day or several days can______(55)health.Several hot days are considered a heat wave.Experts say heat waves often become dangerous when the nighttime temperature does not_______(56)much from the highest daytime temperature.This causes great stress on the human body. Doctors say people can do many things to______(57)themselves from the dangers of extreme heat. Stay out of the sun,if possible.Drink lots of cool water.Wear light colored clothing made______(58) natural materials;avoid wearing synthetic clothing.Make sure the clothing is______(59),permitting freedom of movement.And learn the danger______(60)of the medical problems,such as headache and vomiting,that are linked to heat.Most people suffer only muscle pain as a(n)______(61)of heat stress.The fiain is a______(62)that the body is becoming too hot.Doctors say those suffering headache or muscle pain should stop all activity,rest in a cool place and drink cool liquids.Do not return to physical _______(63)for a few hours because more serious conditions could develop. Doctors say some people face an______(64)danger from heat stress.Such persons have a weak or damaged heart,high blood pressure,or other problems of the blood system. Hot Weather also increases dangers for people who must take______(65)for high blood pressure, poor blood flow,nervousness or depression.61._________A:influence B:result C:effect D:view
考题
共用题干
Heat Is Killer Extremely hot weather is common in many parts of the world.Although hot weather just makes most people feel hot,it can_______(51)serious medical problems-even death.Floods,storms,volcano eruptions and other natural______(52)kill thousands of people every year.So______(53) extreme heat.Experts say heat may be nature's deadliest killer, Recently,extreme heat was blamed ______(54)killing more than one hundred people in India.It is reported that the total heat of a hot day or several days can______(55)health.Several hot days are considered a heat wave.Experts say heat waves often become dangerous when the nighttime temperature does not_______(56)much from the highest daytime temperature.This causes great stress on the human body. Doctors say people can do many things to______(57)themselves from the dangers of extreme heat. Stay out of the sun,if possible.Drink lots of cool water.Wear light colored clothing made______(58) natural materials;avoid wearing synthetic clothing.Make sure the clothing is______(59),permitting freedom of movement.And learn the danger______(60)of the medical problems,such as headache and vomiting,that are linked to heat.Most people suffer only muscle pain as a(n)______(61)of heat stress.The fiain is a______(62)that the body is becoming too hot.Doctors say those suffering headache or muscle pain should stop all activity,rest in a cool place and drink cool liquids.Do not return to physical _______(63)for a few hours because more serious conditions could develop. Doctors say some people face an______(64)danger from heat stress.Such persons have a weak or damaged heart,high blood pressure,or other problems of the blood system. Hot Weather also increases dangers for people who must take______(65)for high blood pressure, poor blood flow,nervousness or depression.64._________A:impossible B:incident C:incredible D:increased
考题
共用题干
How the Body Keeps the Same TemperatureThe temperature of your body should always be the same if you are fine,no matter whether the weather is hot or cold.That is why the doctor tests your temperature with a thermometer when you are sick.Normally, your body teniperature is ninety-eight point six degrees Fahrenheit.If it is_______(51)than that,it is a stire sign that something is wrong with your body.Your body keeps the same temperature all the time,because it balances the heat it produces and theheat it_______(52)off. It is always burning up food and producing heat.It can produce heat faster when the body needs or give off heat faster when the body becomes too warm.Let's see_______(53) this works.The heat of your body is given off chiefly through the skin.When you feel_______(54),your skin is tight and shows"goose flesh".When you feel chilly,you must_______(55)around to keep warm._______(56)your muscles begin to work,bum up fuel and produce more heat.It is not_______(57)toshiver,so you usually prefer warming up by taking exercise,or put_______(58)more clothes to keep warm。When you get warm,the skin is loose and soft. It is so supplied_______(59)blood that heat is giv-en off rapidly. If you get too warm,you begin to sweat and_______(60)body heat is used in evaporating the, moisture in your body.In warm_______(61)or warm rooms,you wear less clothing,_______ (62)heat can be given off freely. You prefer less exercise because your body is warm_______(63),and the extra heat produced by taking too much exercise makes you uncomfortable.Now you see why you_______(64)differently in different kinds of weather. In summer,when it is hot,you feel tired and lazy.You do not care to work or play,but enjoy lying down and doing nothing. When you get out of door in winter,the cold air makes you feel_______(65).You want to run and play._________(61)A:weatherB:climateC:circumstanceD:environment
考题
共用题干
How the Body Keeps the Same TemperatureThe temperature of your body should always be the same if you are fine,no matter whether the weather is hot or cold.That is why the doctor tests your temperature with a thermometer when you are sick.Normally, your body teniperature is ninety-eight point six degrees Fahrenheit.If it is_______(51)than that,it is a stire sign that something is wrong with your body.Your body keeps the same temperature all the time,because it balances the heat it produces and theheat it_______(52)off. It is always burning up food and producing heat.It can produce heat faster when the body needs or give off heat faster when the body becomes too warm.Let's see_______(53) this works.The heat of your body is given off chiefly through the skin.When you feel_______(54),your skin is tight and shows"goose flesh".When you feel chilly,you must_______(55)around to keep warm._______(56)your muscles begin to work,bum up fuel and produce more heat.It is not_______(57)toshiver,so you usually prefer warming up by taking exercise,or put_______(58)more clothes to keep warm。When you get warm,the skin is loose and soft. It is so supplied_______(59)blood that heat is giv-en off rapidly. If you get too warm,you begin to sweat and_______(60)body heat is used in evaporating the, moisture in your body.In warm_______(61)or warm rooms,you wear less clothing,_______ (62)heat can be given off freely. You prefer less exercise because your body is warm_______(63),and the extra heat produced by taking too much exercise makes you uncomfortable.Now you see why you_______(64)differently in different kinds of weather. In summer,when it is hot,you feel tired and lazy.You do not care to work or play,but enjoy lying down and doing nothing. When you get out of door in winter,the cold air makes you feel_______(65).You want to run and play._________(53)A:howB:whenC:whatD:why
考题
单选题The rate of heat transfer from a hot region to a cold region is affected most by the （）.A
size of the heat sinkB
temperature difference between the regionsC
size of the heat sourceD
total heat of the system
考题
单选题Sacrificial zinc anodes are used on the saltwater side of diesel engine heat exchangers to（）.A
reduce electrolytic action on heat exchanger metalsB
keep heat transfer surfaces shiny and cleanC
prevent rapid accumulation of marine growthD
provide a protective coating on heat exchanger surfaces
考题
填空题Our atmosphere absorbs the heat the ground emits and sends some of it back to the Earth.____
考题
单选题The heat gained per pound of refrigerant in the evaporator is known as the（）.A
latent heat of vaporizationB
sensible heatC
refrigerating effectD
specific heat of vaporization
考题
单选题It is required that such insulator (绝热体)．______a heat resistant material.A
must be made ofB
should be made ofC
will be made ofD
would be made of
考题
问答题Practice 1 Heat loss by sweating depends on the fact that when a liquid evaporates, it absorbs an enormous quantity of heat from its surroundings. Therefore, when I am of sweat evaporate, a great deal of heat is absorbed from the surface of the body in contact with it. 1______ 2______ The first is the amount of movement of air surrounding the body. The second is the amount of water vapor in the air that surrounds the body. 3______ For this reason, sweat evaporates very rapidly on windy days, and the rate of heat loss by sweating is much more than on a still day. This accounts for the fact that hot still days are much less comfortable than hot windy days. In contrast, the sweat evaporates very rapidly on hot windy days, and cools the body quickly and effectively. 4______ When air is carrying the maximum amount of water vapor that it can hold, it is said to be 100% saturated with water vapor. The relative humidity of the air is said to be 100%. Under these conditions the air cannot carry any water, so no water can evaporate. When the relative humidity is high, therefore, sweat cannot evaporate. Instead, it forms large drops and runs off your skin without cooling you. 5______ It is obvious that under these conditions, evaporation will be much more rapid. Therefore, sweating will be much more effective as a method of losing heat from the body. On a hot dry day, sweat evaporates as soon as it is formed, and you feel reasonably cool even though the temperature of your environment is very high.[A] When the air is very dry and carries no water at all, the relative humidity is said to be 0%.[B] The second factor is the amount of water vapor in the air－the humidity.[C] Hot windy days are much more comfortable than hot still days.[D] This heat transfer occurs even if the environment is hotter than the body.[E] When air moves over the surface of water, the amount of evaporation is greatly increased.[F] You might expect the highest incidence of a heat stroke when the maximum temperature is 100 and humidity is 50%.[G] Two factors affect the rate of evaporation of sweat, and therefore the effectiveness of sweating as a method of cooling the body.
考题
单选题The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.A
remain constant along the tubes lengthB
be greatest in a single pass counter flow heat exchangerC
remain constant throughout the heat exchangerD
vary from section to section through out the heat exchanger
考题
单选题Which of the following is true of the heating system of the Johnstown campus?A
The heat is supplied by human bodies only.B
The heat is supplied by both human bodies and other heat-emitting objects.C
The heat is supplied by both human bodies and conventional fuel.D
The heat is supplied by human bodies, other heat-emitting objects, and conventional fuel.
考题
单选题The heat used to change a liquid to a vapor is called （）.A
latent heat of fusionB
latent heat of vaporizationC
specific heat of vaporizationD
latent heat of the gas
考题
单选题The heat required to change a substance from a solid to a liquid while at its freezing temperature, is known as the latent heat of （）.A
fusionB
vaporizationC
condensationD
sublimation
考题
单选题The amount of heat released by steam when it changes to water at the same temperature is called（）.A
latent heat of condensationB
latent heat of vaporizationC
latent heat of saturationD
sensible heat of condensation
考题
单选题We learn from the passage that ______.A
all living things on the earth depend on the sun for their foodB
a forest looks dark in winter because it absorbs solar energyC
only 0.023 of the energy from the sun is made use of on the earthD
greenhouse gases allow heat energy to escape from the earth’ s surface
考题
单选题“The use of a poor quality oil can lead to rapid deterioration of its properties with the resultant formation of deposits in the piston crown which in turn results in a considerable reduction in heat transfer with subsequent overheating and thermal cracking” According to this sentence, we can know that the principle reason of the overheating and thermal cracking is（）A
the use of a poor quality oilB
the deterioration of its propertiesC
the formation of depositsD
the reduction in heat transfer ability
考题
单选题Which of the following statements is correct concerning heat transfer?（）A
Heat is given off from a high temperature region known as a heat sinkB
Heat transfer rate is affected most by the size of the heat sink involvedC
Heat transfer rate is affected most by the temperature difference between the heat source and the heat sinkD
Heat transfer by radiation will occur only by mass motion of a fluid substance
考题
单选题A refrigerant gives up heat when it goes through （）.A
condenserB
regurgitateC
evaporatorD
boil coil
热门标签
最新试卷
