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Radar is used to determine the characteristics of radiocarbon.
A．Right
B．Wrong
C．Not mentioned
答案
更多“Radar is used to determine the characteristics of radiocarbon.A．RightB．WrongC．Not mentione”相关的问题
第1题
19 Radar is used to determine the characteristics of radiocarbon.
A Right
B Wrong
C Not mentioned
第2题
As used in the last sentence, the phrase "in short" means ______.
A．in the long run
B．in detail
C．in a word
D．in the end
第3题
To identify planes flying overhead, the U. S. air-traffic controllers used to _____.
A．get information by communication through phone calls
B．depended on the "war room" for information
C．collect data by way of radar
D．use several computers working at the same time
第4题
Radar (雷达)
1. Children enjoy shouting at a high wall and hearing the sound come back to them. These sounds are called echoes (回声). Echoes have given us a number of 'valuable tools.
2. Echo sounding devices were early used in making maps of the ocean floor. Sounds or Ultrasonic (超声的) sounds make good tools for determining how deep the water is under ships. Sometimes echoes from ultrasonic distance finding devices were prevented from working by fish swimming past or by the presence of large objects. So ultrasonic devices have been replaced by other tools.
3. Radar is now a familiar tool. Like many others it was ah unexpected discovery. It was first observed by two researchers, who were studying sound communication. They were sending signals from a station on one side of a river in Washington, D .C. to a vehicle across the river. They discovered that their signals were stopped by passing ships. They recognized the importance of this discovery at once.
4. All this was of course just a start, from which our present radar has developed. The word "radar," in fact, gets its name from the term "radio detection (检测) and ranging." "Ranging" is the term for detection of the distance between an object and the radar set. Today, in our scientific age, it would be difficult to manage without radar.
5. One of the many uses of radar is as a speed control device on highways. When a person in an automobile is driving faster than the speed limit, radar will show this clearly and the traffic police can take measures to stop him.
6. A pilot cannot fly a plane by sight alone. Many conditions such as flying at night and landing in dense fog require the pilot to use radar. Human eyes are not very good at determining speeds of approaching objects, but radar can show the pi lot how fast nearby planes are moving.
A Study of Sound
B Highway Police
C Working Principles
D Early Use of "Radar"
E Useful Tools
F Discovery by Chance
Paragraph 2 ______
第5题
To get a full appreciation of what this means we must turn first to some recent human inventions. Everyoneknows that if he shouts near a wall or a mountainside, an echo will come back. The further off this solid obstacle, the longer time it will take for the return of the echo. A sound made by tapping on the main body of a ship will be reflected from the sea bottom, and by measuring the time interval between the taps andthe receipt of the echoes the depth of the sea at that point can be calculated.So was born the echo-sounding equipment, now in general use in ships. Every solid object will reflect a sound, varying according to the size and nature of the object. A shoal of fish will do this. So it is a comparatively simple step fromlocating the sea bottom to locating a shoal of fish. With experience, and with improved equipment, it is now possible not only to locate fish but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.
A few years ago it was found that certain bats emit squeaks (吱吱声) and by receiving ’he echoes they could locate and steer clear of obstacles--or locate flying insects on which they feed.This echolocation in bats is often compared with radar, the principle of which is similar.@@@@@@@ Choose correct answers to the question:
The main purpose of this passage is to ______.
A.describe that animals can make different sounds
B.prove that animals’ voices can play practical roles
C.inspire the readers to make more inventions
D.startle the readers with some shocking facts
The discovery of echolocation may help with all of the following EXCEPTA.measuring the depth of the sea
B.distinguishing different kinds of fish
C.improving the functions of radar
D.varying the size and nature of an object
By saying "A shoal of fish will do this"(Lines 6-7, Para 2), the author means ________.A.only one special kind of fish can reflect sounds
B.only one special kind of fish can be used to help locate a ship
C.a large group of fish can reflect sounds
D.a large group of fish can be used to help locate a ship
As it is discussed in the passage, the squeaks of bats can be functionally compared with ________.A.human languages
B.a mountainside
C.a shoal of fish
D.taps on a ship
Which of the following statements can be inferred from the passage？A.Animals are more intelligent than humans.
B.Humans are more intelligent than animals.
C.Animals are often compared with human inventions.
D.Humans are often inspired by animals.
请帮忙给出每个问题的正确答案和分析，谢谢！
第6题
【C1】______ nearly a hundred years of powered flight, scientists are still trying to figure out how birds fly.
Researchers have learned that the slapping noise pigeons make when they suddenly take off is the sound of super charged lift. They call it the "clap fling" effect.
Here at SRI International scientists try to duplicate the pigeons' thrust. A flashing strobe reveals the secret.
Scott Stanford, a scientist at SRI, says, You re looking at the clap fling effect, where the two wings will come together and peel apart 【C2】______ each other, thus augmenting lift 【C3】______ drawing air from the top to the bottom. "
This mechanical bug won't get off the ground. 【C4】______ its flapping wings demonstrate a potential propulsion system for robotic birds: man-made rubbery muscle.
Roy Kornbluh works at SRI. "There, I'm turning the voltage on and off, and you can see when the voltage is on, the material is larger 【C5】______ when the voltage is off."
Super computers show high-speed airflows over supersonic aircraft.
But scientists have only begun to see how air flows 【C6】______ really low speeds.
Professor Max Platzer of the Naval Postgraduate School, says, "The flapping wing is generating a thrust, this way, this is the basic physics of the phenomenon."
It's pelicans--not pigeons--the Navy is looking at. The Navy is looking at the smooth easy flight of pelicans low over water--called "ground effect." Researchers at the Naval Postgraduate School are trying to imitate the pelican's efficiency.
Assistant Professor Kevin Jones of the Naval Postgraduate School says, " 【C7】______ flapping the wings, symmetrically, we're 【C8】______ effect imitating ground effect. We now have the same feature a bird sees when it's flying, over a ground plane."
An electric motor drives the flapping wings. Researchers here are working 【C9】______ ways to beam power to the tiny bird.
David Jenn of the Naval Postgraduate School says, "There's no battery inside of here, so we're going to set this inside the radar beam, and the energy is extracted from the radar beam and will be used to propel the motor."
Scientists are learning it's one thing to build an airplane, 【C10】______ quite another to build a bird.
【C1】______
第7题
根据下列文章,请回答 23～30 题。
Electromagnetic Energy
1 White light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared (红外线的) radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays (紫外线) and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so much energy that they travel right through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to Operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too.
5 Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed (利用) by man. Chemical energy comes from electron (电子) rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium (氦).
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy.
第 23 题 Paragraph 3__________
A．Nuclear Reactions as the Lasting Source of the Sun's Energy
B．The Most Important Source of Energy
C．Types of Electromagnetic Energy
D．The Machines Used for Energy Generation
E．Seeking New Sources of Energy
F．The Use of Ultraviolet Radiation in Medicine
第8题
回答题。
Electromagnetic Energy
1. White light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.
2. The sun is 93 million miles from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space.
3. Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared (红外线的 ) radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays (紫外线 ) and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so mush energy that they travel right through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones.
4. Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too.
5. Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed (利用 ) by man. Chemical energy comes from electron (电子 ) rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun&39;s energy comes from the nuclear reactions in which hydrogen is changed into helium (氦 ) .
6. Nuclear energy is beginning to compete with coal as an economical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy.
Paragraph 3__________ 查看材料
A.Nuclear reactions as the lasting source of the sun"s energy
B.The most important source of energy
C.Types of electromagnetic energy
D.The machines used for energy generation
E.Seeking new sources of energy
F.The use of ultraviolet radiation in medicine
第9题
Renewable Energy Sources
Today petroleum (石油)provides around 40% of the world's energy needs, mostly fuelling automobiles. Coal is still used, mostly in power stations, to cover one-quarter of our energy needs, but it is the least efficient, unhealthiest and most environmentally damaging fossil fuel (矿物燃料). Natural gas reserves could fill some of the gap from oil, but reserves of that will not last into the 22nd century either. Most experts predict we will exhaust easily accessible reserves within 50 years. Less-polluting renewable energy sources offer a more practical long-term energy solution. "Renewable" refers to the fact that these resources are not used faster than they can be replaced.
Hydroelectric (水力发电的)power is now the most common form. of renewable energy, supplying around 20% of world electricity. China's Three Gorges Dam is the largest ever. At five times the size of the US's Hoover Dam, its 26 turbines (涡轮机)will generate the equivalent energy of 18 coal-fired power stations. It will satisfy 3% of China's entire electricity demand.
In 2003, the first commercial power station to use tidal (潮汐的)currents in the open sea opened in Norway. It is designed like windmill (风车), but others take the form. of turbines.
As prices fall, wind power has become the fastest growing type of electricity generation-quadrupling (翻两番)worldwide between 1999 and 2005. Modern wind farms consist of turbines that generate electricity. Though it will be more expensive, there is more than enough wind to provide the world's entire energy needs. Wind farms come in onshore and offshore forms. They can often end up at spots of natural beauty, and are often unpopular with residents. And turbines are not totally harmless-they can interfere with radar, alter climate and kill sea birds. Scotland is building Europe's largest wind farm, which will power 200, 000 homes. The UK's goal is to generate one-fifth of power from renewable sources, mainly wind, by 2020. But this may cause problems, because wind is unreliable.
According to the passage, which of the following is the most polluting energy resource？
A．Petroleum.
B．Coal.
C．Natural gas
D．Water.
第10题
Renewable Energy Sources Today petroleum(石油)provides around 40% of the world’s energy needs,mostly fuelling automobiles.Coal is still used,mostly in power stations,to cover one-quarter of our energy needs,but it is the least efficient,unhealthiest and most environmentally damaging fossil fuel(矿物燃料).Natural gas reserves could fill some of the gap from oil,but reserves of that will not last into the 22nd century either.Most experts predict we will exhaust easily accessible reserves within 50 years.Less-polluting renewable energy sources offer a more practical long-term energy solution.“Renewable”refers to the fact that these resources are not used faster than they can be replaced.
Hydroelectric(水力发电的)power is now the most common form. of renewable energy,supplying around 20% of world electricity.China’s Three Gorges Dam is the largest ever.At five times the size of the US’s Hoover Dam,its 26 turbines(涡轮机)will generate the equivalent energy of 18 coal-fired power stations.It will satisfy 3% of China’s entire electricity demand.
In 2003,the first commercial power station to use tidal(潮汐的)currents in the open sea opened in Norway.It is designed like windmill(风车),but others take the form. of turbines.
As prices fall,wind power has become the fastest growing type of electricity generation-quadrupling(翻两番)worldwide between 1999 and 2005.Modern wind farms consist of turbines that generate electricity.Though it will be more expensive,there is more than enough wind to provide the world’s entire energy needs.Wind farms come in onshore and offshore forms.They can often end up at spots of natural beauty,and are often unpopular with residents.And turbines are not totally harmless-they can interfere with radar,alter climate and kill sea birds.Scotland is building Europe’s largest wind farm,which will power 200,000 homes.The UK’s goal is to generate one-fifth of power from renewable sources,mainly wind,by 2020.But this may cause problems,because wind is unreliable.
第11题：According to the passage,which of the following is the most polluting energy resource？
A．Petroleum.
B．Coal.
C．Natural gas
D．Water.
