2010年12月大学英语六级真题听力mp3和文本下载

Section B
Passage One
Among global warming’s most frightening threats is the prediction is that the polar ice-caps will melt, raising sea level so much that coastal cities from New York to Los Angles to Shanghai will be flooded. Scientists agree that key player in this scenario is the West Antarctic ice sheet, a Brazil-size mass of frozen water that is much as 7000 feet thick. Unlike floating ice shelves which have little impact on sea level when they break up, the ice sheet is anchored to bedrock will blow the sea surface. Surrounded by open ocean, it is also vulnerable, but Antarctic experts disagree strongly on just how unstable it is. Now, new evidence reveals that all or most of the Antarctic ice sheet collapsed at least once during the past 1.3 million years, a period when global temperatures probably were not significantly higher than they are today. And the ice sheet was assumed to have been stable. In geological time, a million years is recent history. The proof, which was published last week in Science, comes from a team of scientists from Uppsala University in Sweden and California Institute of Technology who drew deep holes near the edge of ice sheet. Within samples collected from the solid substances lying beneath the ice. They found fossils of microscopic marine plants which suggest that the region was once open ocean not solid ice. As Herman Engleheart, a co-author from the California Institute of Technology says, ‘the West Antarctic ice sheet disappear once and can disappear again.’

26. What is one of the most frightening threats of global warming according to the passage?

27. What did scientists disagree on?

28. What is the latest information revealed about the West Antarctic ice sheet?

29. What the scientists’ latest findings suggest?

Passage Two
It's always fun to write about research that you can actually try out for yourself.

Try this: Take a photo and upload it to Facebook, then after a day or so, note what the URL link to the picture is and then delete it. Come back a month later and see if the link works. Chances are: It will.

Facebook isn't alone here. Researchers at Cambridge University have found that nearly half of the social networking sites don't immediately delete pictures when a user requests they be removed. In general, photo-centric websites like Flickr were found to be better at quickly removing deleted photos upon request.

Why do "deleted" photos stick around so long? The problem relates to the way data is stored on large websites: While your personal computer only keeps one copy of a file, large-scale services like Facebook rely on what are called content delivery networks to manage data and distribution. It's a complex system wherein data is copied to multiple intermediate devices, usually to speed up access to files when millions of people are trying to access the service at the same time. But because changes aren't reflected across the content delivery networks immediately, ghost copies of files tend to linger for days or weeks.

In the case of Facebook, the company says data may hang around until the URL in question is reused, which is usually "after a short period of time", though obviously that time can vary considerably.

30. What does the speaker ask us to try out?

31. What accounts for the failure of some websites to remove photos immediately?

32. When will the unwanted data eventually disappear from Facebook according to the company?

Passage Three
Enjoying an iced coffee? Better skip dinner or hit the gym afterwards, with a cancer charity warning that some iced coffees contain as many calories as a hot dinner.

The World Cancer Research Fund (WCRF) conducted a survey of iced coffees sold by some popular chains in Britain including Starbucks, Caffe Nero and Costa Coffee to gauge the calories as studies increasingly link obesity with cancer.

The worst offender - a coffee from Starbucks -- had 561 calories. Other iced coffees contained more than 450 calories and the majority had an excess of 200.

Health experts advise that the average woman should consume about 2,000 calories a day and a man about 2,500 calories to maintain a healthy weight. Dieters aim for 1,000 to 1,500 calories a day.

"The fact that there is an iced coffee on the market with over a quarter of a woman's daily calories allowance is alarming," Dr Rachel Thompson, science programme manager at London-based WCRF, said in a widely-reported statement.

"This is the amount of calories you might expect to have in an evening meal, not in a drink."

The WCRF has estimated that 19,000 cancers a year in Britain could be prevented if people lost their excess weight with growing evidence that excess body fat increases the risk of various cancers.

"If you are having these types of coffee regularly then they will increase the chances of you becoming overweight, which in turn increases your risk of developing cancer, as well as other diseases such as heart disease." she added.

33. What warning did some health experts give?

34. What does the author suggest people do after they have an iced coffee?

35. What could British people expect if they maintain a normal body weight according to the WCRF?