场field

在交错视频中，每一帧由两个场（Field）构成，称为奇场和偶场，在Premierepro中称为上场和下场，这些场依顺序显示在NTSC或PAL制式的监视器上。其中奇数场可以对应（）。

A:Even field B:odd field C:upper field D:lower field

Text 4
Can electricity cause cancer In a society that literally runs on electric power, the very idea seems preposterous. But for more than a decade, a growing band of scientists and journalists has pointed to studies that seem to link exposure to electromagnetic fields with increased risk of leukemia and other malignancies. The implications are unsettling, to say the least, since everyone comes into contact with such fields ,which are generated by everything electrical, from power lines and antennas to personal computers and micro-wave ovens. Because evidence on the subject is inconclusive and often contradictory, it has been hard to decide whether concern about the health effects of electricity is legitimate or the worst kind of paranoia.
Now the alarmists have gained some qualified support from the US Environmental Protection Agency. In the executive summary of a new scientific review, released in draft form late last week, the EPA has put forward what amounts to the most serious government warning to date. The agency tentatively concludes that scientific evidence "suggests a casual link" between extremely low-frequency electromagnetic fields-- those having very long wave-lengths and leukemia, lymphoma and brain cancer. While the report falls short of classifying ELF fields as probable carcinogens, it does identify the common 60-hertz magnetic field as "a possible, but not proven, cause of cancer in humans."
The report is no reason to panic or even to lost sleep. If there is a cancer risk, it is a small one. The evidence is still so controversial that the draft stirred a great deal of debate within the Bush Administration, and the EPA released it over strong objections from the Pentagon and the White House. But now no one can deny that the issue must be taken seriously and that much more research is needed.
At the heart of the debate is a simple and well-understood physical phenomenon: When an electric current passes through a wire, it generates an electromagnetic field that exerts forces on surrounding objects. For many years, scientists dismissed any suggestion that such forces might be harmful, primarily because they are so extraordinarily weak. The ELF magnetic field generated by a video terminal measures only a few milli gauss, or about one-hundredth the strength of the earth’ s own magnetic field. The electric fields surrounding a powers line can be as high as 10 kilovolts per meter, but the corresponding field induced in human cells will be only about 1 millivolt per meter. This is far less than the electric fields that the cells themselves generate.
How could such minuscule forces pose a health danger The consensus used to be that they could not, and for decades scientists concentrated on more powerful kinds of radiation, like X-rays, that pack sufficient wallop to knock electrons out of the molecules that make up the human body. Such "Ionizing" radiations have been clearly linked to increased cancer risks and there are regulations to control emissions.
But epidemiological studies, which find statistical associations between sets of data, do not prove cause and effect. Though there is a body of laboratory work showing that exposure to ELF fields can have biological effects on animal tissues, a mechanism by which those effects could lead to cancerous growths has never been found.
The Pentagon is far from persuaded. In a blistering 33-page critique of the EPA report, Air Force scientists charge its authors with having "biased the entire document" toward proving a link. "Our reviewers are convinced that there is no suggestion that (electromagnetic fields) present in the environment induce or promote cancer," the Air Force concludes, "It is astonishing that the EPA would lend its imprimatur on this report." The Pentagon’ s concern is understandable. There is hardly a unit of the modern military that does not depend on the heavy use of some kind of electronic equipment, from huge ground-based radar towers to the defense built into every warship and plane.

It can be inferred from physical phenomenon（）

A:the force of the electromagnetic field is too weak to be harmful B:the force of the electromagnetic field is weaker than the electric field that the cells generate C:electromagnetic field may affect health D:only more powerful radiation can knock electron out of human body

Your eye is a window on the nerves and blood vessels, revealing vital information about your entire body. An (1) exam starts from the outside and works in. First the ophthalmologist (眼科医生) gauges (2) with the familiar wall chart and checks visual field by moving objects in and out of (3) . A limited visual field could be the (4) of the high inner eye pressure of glaucoma(青光眼)or (5) a tumor pressing on nerves leading from the eye. The physician also checks for infection around the lashes and notes how fast the lids follow the eyes downward. Lid lag sometimes (6) thyroid disease (甲状腺疾病).
If one pupil contracts (7) the other doesn’t, the physician is (8) to the fact that (9) a tumor or stroke, perhaps, has damaged the nerves between the eye and brain. A tumor as far away (10) the lung can cause capillary problems by hitting a nerve that loops through the neck.
The white of the eye, tear ducts, lens and retina (视网膜) are checked for (11) of trouble. Too many white blood cells (12) inflammation, blood means tissue has tom or a vessel has burst, and deposits of (13) material can mean eye disease. The orange-red retina holds many more (14) for disease detection. High blood pressure may announce its (15) by pushing the vessels off track at their intersections. (16) vessel growth is a sign of diabetic retinopathy (糖尿病性视网膜病). Narrowed vessels may indicate (17) of the arteries, and damage to tiny capillaries could be a sign of early diabetes.
The doctor even examines the pin-head-size hole in the back of the optic nerve on their way to the brain. (18) the appearance of these nerve fibers is abnormal, nerve tissue may have been damaged because of intraocular pressure, indicating glaucoma or the presence of a tumor. When a physician needs quick, (19) information about the body, the eyes have (20) .

Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C or D on ANSWER SHEET 1.2（）

A:temperature B:health C:field D:vision

Text 4 Can electricity cause cancer In a society that literally runs on electric power, the very idea seems preposterous. But for more than a decade, a growing band of scientists and journalists has pointed to studies that seem to link exposure to electromagnetic fields with increased risk of leukemia and other malignancies. The implications are unsettling, to say the least, since everyone comes into contact with such fields ,which are generated by everything electrical, from power lines and antennas to personal computers and micro-wave ovens. Because evidence on the subject is inconclusive and often contradictory, it has been hard to decide whether concern about the health effects of electricity is legitimate or the worst kind of paranoia. Now the alarmists have gained some qualified support from the US Environmental Protection Agency. In the executive summary of a new scientific review, released in draft form late last week, the EPA has put forward what amounts to the most serious government warning to date. The agency tentatively concludes that scientific evidence "suggests a casual link" between extremely low-frequency electromagnetic fields-- those having very long wave-lengths and leukemia, lymphoma and brain cancer. While the report falls short of classifying ELF fields as probable carcinogens, it does identify the common 60-hertz magnetic field as "a possible, but not proven, cause of cancer in humans." The report is no reason to panic or even to lost sleep. If there is a cancer risk, it is a small one. The evidence is still so controversial that the draft stirred a great deal of debate within the Bush Administration, and the EPA released it over strong objections from the Pentagon and the White House. But now no one can deny that the issue must be taken seriously and that much more research is needed. At the heart of the debate is a simple and well-understood physical phenomenon: When an electric current passes through a wire, it generates an electromagnetic field that exerts forces on surrounding objects. For many years, scientists dismissed any suggestion that such forces might be harmful, primarily because they are so extraordinarily weak. The ELF magnetic field generated by a video terminal measures only a few milli gauss, or about one-hundredth the strength of the earth’ s own magnetic field. The electric fields surrounding a powers line can be as high as 10 kilovolts per meter, but the corresponding field induced in human cells will be only about 1 millivolt per meter. This is far less than the electric fields that the cells themselves generate. How could such minuscule forces pose a health danger The consensus used to be that they could not, and for decades scientists concentrated on more powerful kinds of radiation, like X-rays, that pack sufficient wallop to knock electrons out of the molecules that make up the human body. Such "Ionizing" radiations have been clearly linked to increased cancer risks and there are regulations to control emissions. But epidemiological studies, which find statistical associations between sets of data, do not prove cause and effect. Though there is a body of laboratory work showing that exposure to ELF fields can have biological effects on animal tissues, a mechanism by which those effects could lead to cancerous growths has never been found. The Pentagon is far from persuaded. In a blistering 33-page critique of the EPA report, Air Force scientists charge its authors with having "biased the entire document" toward proving a link. "Our reviewers are convinced that there is no suggestion that (electromagnetic fields) present in the environment induce or promote cancer," the Air Force concludes, "It is astonishing that the EPA would lend its imprimatur on this report." The Pentagon’ s concern is understandable. There is hardly a unit of the modern military that does not depend on the heavy use of some kind of electronic equipment, from huge ground-based radar towers to the defense built into every warship and plane.

It can be inferred from physical phenomenon （）

A:the force of the electromagnetic field is too weak to be harmful B:the force of the electromagnetic field is weaker than the electric field that the cells generate C:electromagnetic field may affect health D:only more powerful radiation can knock electron out of human body

(According to) our estimate, only one (out of) three company managers (have been) trained in the (field of) management.（　）

A:According to B:out of C:have been D:field of

{{B}}第三篇{{/B}}

What have the two French geophysicists discovered in their research?

A:Some regularity in the changes of the earth’s magnetic field, B:Some causes of the fluctuation of the earth’s magnetic field, C:The origin of the earth’s magnetic field. D:The frequency of polarity reversals.

第一篇 The Northern Lights The sun is stormy and has it own kind of weather. It is so hot and active that even the Sun’s gravity cannot hold its atmosphere in check! Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma, and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun, the stronger the solar wind. The solar wind constantly streams toward the Earth, but don’t worry because a protective magnetic fields surrounds our planet. The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles. The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth’s magnetic field first gets squeezed and then the magnetic field lines break and reconnect. The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth’s atmosphere at the poles. As the electrons fall into the Earth, they collide with gas molecules in the atmosphere, creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky, they create the Northern Lights and the Southern Lights. Watching auroras(北极光) is fun and exciting, but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate(跳动), flicker(闪烁), or even move like waves. During solar maximum, 5 auroras are seen as far south as Florida, even Mexico!Auroras often seem to be very close to the ground, but the lowest aurora is still about 100 kilometers above the ground, a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long, a few hundred kilometers high, but only a few hundred meters thick. We hope you are able to travel to far-north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!What happens when solar wind comes to the Earth?

A:A protective magnetic field is formed at the same time. B:It is trapped in magnetic belts around the Earth. C:It destroys the protective magnetic field surrounding the Earth. D:It breaks magnetic field lines and does severe damage to the ?