题目内容
It has been known for many decades that the appearance of sunspots is roughly periodic, with an average cycle of eleven years. Moreover, the incidence of solar flares and the flux of solar cosmic rays, ultraviolet radiation, and X-radiation all vary directly with the sunspot cycle. But after more than a century of investigation, the relation of these and other phenomena, known collectively as the solar-activity cycle, to terrestrial weather and climate remains unclear. For example, the sunspot cycle and the allied magneticpolarity cycle have been linked to periodicities discerned in records of such variables as rainfall, temperature, and winds. Invariably, however, the relation is weak, and commonly of dubious statistical significance.
Effects of solar variability over longer terms have also been sought. The absence of recorded sunspot activity in the notes kept by European observers in the late seventeenth and early eighteenth centuries has led some scholars to postulate a brief cessation of sunspot activity at that time (a period called the Maunder minimum). The Maunder minimum has been linked to a span of unusual cold in Europe extending from the sixteenth to the early nineteenth centuries. The reality of the Maunder minimum has yet to be established, however, especially since the records that Chinese naked-eye observers of solar activity made at that time appear to contradict it. Scientists have also sought evidence of long-term solar periodicities by examining indirect climatological data, such as fossil records of the thickness of ancient tree rings. These studies, however, failed to link unequivocally terrestrial climate and the solar-activity cycle, or even to confirm the cycle's past existence.
If consistent and reliable geological or archaeological evidence tracing the solar-activity cycle in the distant past could be found, it might also resolve an important issue in solar physics, how to model solar activity. Currently, there are two models of solar activity. The first supposes that the Sun's internal motions (caused by rotation and convection) interact with its large-scale magnetic field to produce a dynamo, a device in which mechanical energy is converted into the energy of a magnetic field. In short, the Sun's large-scale magnetic field is taken to be self-sustaining, so that the solar-activity cycle it drives would be maintained with little overall change for perhaps billions of years. The alternative explanation supposes that the Sun's large-scale magnetic field is a remnant of the field the Sun acquired when it formed, and is not sustained against decay. In this model, the solar mechanism dependent on the Sun's magnetic field runs down more quickly. Thus, the characteristics of the solar-activity cycle could be expected to change over a long period of time. Modern solar observations span too short a time to reveal whether present cyclical solar activity is a long-lived feature of the Sun, or merely a transient phenomenon.
The author focuses primarily on ______.
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听力原文： Pope John Paul in a visit to Germany is trying to ease the historic division between Catholics and Protestants by saying both groups share blame for the 16th century schism led by Martin Luther. VOA's Karl King reports while praising four German church figures for their opposition to Nazism, the Pope pulled back from prepared remarks defending the church's role during the Hitler regime. Church official has no explanation for the Pope's decision to omit remarks from a prepared speech he delivered at an open-air mass outside the northwestern city of Patagon. The remarks which were in the text delivered to, reporters before the event defended the church's role during the Nazi time and claimed the church played a broad role in resistance to Hitler. Analysts who were watching the Pope's visit say the remarks he dropped from his mass had appeared to contradict his own bishops in Germany who said the church did not do enough to resist the Nazi regime. On Sunday, the Pope travels to Berlin where he will beatify a priest who died in jail after giving sermons against the presecution of the Jews and another who was sent to a concentration camp for expressing regret that Hitler did not die in an assassination attempt. Analysts say the Pope's 3day visit is aimed at shoring up support in Germany Where there has been some descent to authority in Rome. More than one million Catholics in Germany signed a petition last year asking the Pope to relax his opposition to birth-control. So far Pontiff has shown no sign of giving in to the demand.
In a visit to Germany, Pope John Paul said ______ is responsible for the 16th century schism led by Martin Luther.
下面哪一条成立时,称X→Y为平凡的函数依赖？
These marshes are the breeding ground for snow geese. Once destroyed, some fear the species will take over the habitat of the Canada goose —a popular game bird in Minnesota. If this happens, Minnesota hunting and land conditions could be greatly affected.
The snow goose population has been on the rise in the last 25 years, but numbers are hitting an all-time high. This year there is an estimated 4.5 or 6 million birds, triple what the population was 25 years ago.
Although effects of the snow goose invasion aren't apparent in Minneapolis, northern Minnesota and Canada can clearly see the signs. The population growth is due to the birds' wintering habits. They fly south to Louisiana, Texas and Mississippi to nest. The conditions and food availability there have made it possible for more birds to survive the winter and make the trip back north. The period over which they've increased in number correlates to a change in agriculture practices in the region.
After World War Ⅱ, there was an increase in man-made fertilizers, yielding an increase of corn, rice, wheat and other crops. "There have also been other changes in agricultural practices causing an increase of production in cereal crops.
The geese find the agricultural areas better than the natural areas. The geese have escaped from any natural limits. They are not doing this on their own, it is in response to human practices.
Usually, about 70 to 75 percent of the birds make it back to Canada in late winter and early spring. But the surviving number of snow geese has steadily climbed each year to reach 95 percent in the last couple of years. Because so many survive, they strip the capacity of the breeding ground.
The snow geese are destroying salt marshes where they nest in the summer, about 30 percent of the salt marshes are completely destroyed, leaving them as inhabitable mud flats. Another 35 percent of salt marshes are significantly damaged.
There are three possible solutions: Let the problem take care of itself and wait for the population to crash, deal directly with the population by changing hunting limits and regulations or address the cause of the problem in the south.
According to the author, if the northern marshes are destroyed,______.
SECTION B INTERVIEW
Directions: In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. Questions 1 to 5 are based on an interview. At the end of the interview you will be given 10 seconds to answer each of the following five questions.
Now listen to the interview.
听力原文：Policeman: Now, sir, I'm sorry to have kept you waiting. I had to look after the traffic on the road until some more police arrived. You're the driver of the blue ear, I believe.
Mr Simpson: Yes.
Policeman: Just a few questions, sir. Do you feel all right？
Mr Simpson: Yes, I'm...I'm fine now. I was a little shaken up at first.
Policeman: Well, I'll try not to keep you long. I just want a few details, and the rest of the information I can get tomorrow. Can I have your name and address, please？
Mr Simpson: Jeremiah Simpson, 15 Portland Crescent, Leeds.
Policeman: Have you got your driving license and insurance certificate with you？
Mr Simpson: Yes... Oh, here they are.
Policeman: M' Inn... Thank you... Oh... Yes, they're all right. Now, were there any passengers in the car？
Mr Simpson: Er yes, er my wife and a friend -- a young lady. My wife was sitting in the back and her friend in the front passenger seat.
Policeman: Where are they now？
Mr Simpson: The ambulance has just taken them to hospital. You spoke to the ambulance driver before he set off. Did he say anything about the young lady？
Policeman: He said that her injuries looked worse than they really were. The other woman --- that'd be your wife, I assume -- appeared to be suffering from shock.
Mr Simpson: Yes, I know. They advised her to go to hospital for a check-up, just in case...
Policeman: Mm. Was the young lady wearing her seat-belt？
Me Simpson: No, unfortunately. I told her to put it on, but she couldn't adjust it. I didn't think it was worth stopping the car because we were only going a few miles.
Policeman: Did she go through the windscreen？
Mr Simpson: No, she was very lucky. But she hurt her leg on the dashboard.
Policeman: Mm. It could've been much worse. Now, sir, will you tell me in your own words what happened？
Mr Simpson: Oh... Well, as you can see, I was travelling along this main road when suddenly er the other car came out of er that side street. It all happened so quickly. I just didn't see him until he hit me.
Policeman: I've just spoken to the other motorist and he says that you were speeding.
Mr Simpson: What？
Policeman: Is this true？
Mr Simpson: That's a lie. My wife and Becky'll tell you that I stopped at the pedestrian crossing just down them. You can see it's only fifty yards away. I could hardly have reached thirty miles an hour by the time I got here. Goodness knows what would've happened if I'd been going faster.
Policeman: The other driver said that he stopped at the junction. When he pulled out there was nobody coming, so you must at the junction. When he pulled out there was nobody coming, so your must have been speeding.
Mr Simpson: Well, it's not true. I've witnesses to prove it. He couldn't have stopped. The lighting is very good here along this stretch.
Policeman: Yes. He should have stopped. Why did you stop at the pedestrian crossing？
Mr Simpson: There were two old ladies on it. I'm always a bit careful with old people because they're likely to walk across the road without looking properly.
Policeman: I shouldn't worry, sir. We don' t think you were speeding -- even without measuring the skid marks.
Mr Simpson: Er, was he -- er, the other driver -- drunk？
Policeman: I don't know yet. He's admitted that he's had one or two drinks, but says it was only two half-pints. We're going to give him a breathalyser test to see whether he's over the limit. If he is, he'll be asked to have a blood test.
Mr Simpson: Well, I haven't touched a drop all night!
Policeman: No, sir. It's surprising how much a driver's b
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