大學英語四級聽力訓練
大學英語四級聽力訓練不在一朝一夕，而在於長長久久的決心。下面是本站小編給大家整理的大學英語四級聽力訓練美文的相關知識，供大家參閱!
Hotter or Colder ?
It was once thought that air pollution affected only the area immediately around large citieswith factories and/or heavy automobile traffic.
Today, we know that although these are the areas with the worst air pollution, the problem isliterally worldwide.
On several occasions over the past decade, a heavy cloud of air pollution has covered theentire eastern half of the United States and led to health warnings even in rural areas awayfrom any major concentration of manufacturing and automobile traffic.
In fact, the climate of the entire earth may be affected by air pollution.
Some scientists feel that the increasing concentration of carbon dioxide in the air resultingfrom the burning of fossil fuels (coal and oil) is creating a “greenhouse effect” — holding inheat reflected from the earth and raising the world's average temperature.
If this view is correct and the world's temperature is raised only a few degrees, much of thepolar ice cap will melt and cities such as New York, Boston, Miami, and New Orleans will be underwater.
Another view, less widely held, is that increasing particulate matter in the atmosphere isblocking sunlight and lowering the earth's temperature — a result that would be equallydisastrous.
A drop of just a few degrees could create something close to new ice age and would makeagriculture difficult or impossible in many of our top farming areas.
At present we do not know for sure that either of these conditions will happen (though onerecent government report prepared by experts in the field concluded that the greenhouseeffect is very likely).
Perhaps, if we are very lucky, the two tendencies will offset each other and the world'stemperature will stay about the same as it is now.
大學英語四級聽力訓練美文2People with Disabilities
People with disabilities acomprise a large part of the population.
It is estimated that over 35 million Americans have physical, mental, or other disabilities.
About half of these disabilities are “developmental”, i.e., they occur prior to the individual'stwenty-second birthday, often from genetic conditions, and are severe enough to affect threeor more areas of development, such as mobility, communication, employment, etc.
Most other disabilities are considered “adventitious”, i.e., accidental or caused by outsideforces.
Prior to the 20th century, only a small percentage of people with disabilities survived for long.
Medical treatment for these disabilities was unavailable.
Advancements in medicine and social services have created a climate in which people withdisabilities can expect to have such basic needs as food, shelter, and medical treatment.
Unfortunately, these basics are often not available.
Civil liberties such as the right to vote, marry, get an education, and gain employment havehistorically been denied on the basis of disability.
In recent decades, the disability rights movement has been organized to fight against theseinfringements of civil rights.
Congress responded by passing major legislation recognizing people with disabilities as aprotected class under civil rights statutes.
Still today, people with disabilities must fight to live their lives independently.
It is estimated that more than half of qualified Americans with disabilities are unemployed, anda majority of those who do work are underemployed.
About two-thirds live at or below the official poverty level.
Significant barriers, especially in transportation and public awareness, prevent disabledpeople from taking part in society.
For example, while no longer prohibited by law from marrying, a person with no access totransportation is effectively excluded from community and social activities which might leadto the development of long-term relationships.
大學英語四級聽力訓練美文3Will Man Conquer Space?
Man will never conquer space.
Such a statement may sound absurd, after we have made such long strides into space.
Yet it expresses a truth that our forefathers knew and we have forgotten， one that ourdescendants must learn again, in heartbreak and loneliness.
Our age is in many ways unique, full of phenomena that never occurred before and may nevercome again.
They distort our thinking, making us believe that what is true now will be true forever, thoughperhaps on a larger scale.
Because we have annihilated distance on this planet, we imagine that we can do the same inspace.
The truth is otherwise, and we will see it more clearly if we forget the present and turn ourminds toward the past.
To our ancestors, the vastness of the earth was a dominant factor in their thoughts and lives.
No man could ever see more than a tiny fraction of the earth.
Only a lifetime ago, parents waved farewell to their emigrating children, knowing they wouldnever see them again.
Now, within one incredible generation, all this has changed.
Psychologically as well as physically, there are no longer any remote places on earth.
When a friend leaves for what was once a distant country, he cannot feel the same sense ofirrevocable separation that saddened our forefathers.
We know that he is only hours away by air, and we have merely to reach for the telephone tohear his voice.
When the satellite communication network is fully established, it will be as easy to seefriends on the far side of the earth as to talk to them on the other side of the town.
Then the world will shrink no more.
From a world that has become too small, we are moving out into one that will be forever toolarge, whose frontiers will recede from us always more swiftly than we can reach out towardthem.
