新标准大学英语视听说(Unit1-7)听力原文

When you have a biscuit with your cup of tea do you dunk it? And if so what is the perfect way to do it? That's the subject of today's Science in Action Report. It may be hard to believe, but scientists at the University of Bristol have been analyzing this question. And after a two-month study, they devised a mathematical formula for dunking biscuits. So no more melting chocolate, or biscuit crumbs in the bottom of your cup, which is the fate of one in four biscuits that are dunked in tea, according to research by a biscuit manufacturer.

Doughnut bunkers don't face the same problems because doughnuts are held together with an elastic net of protein gluten. This substance allows the doughnut to absorb liquid without breaking down its structure. The structure of a biscuit, however, is held together by sugar which melts when placed in hot tea or coffee. So what is the answer? The researchers, led by Dr Len Fisher, discovered that holding the biscuit in a horizontal position or \biscuit can stay in hot liquid before falling apart. In fact this horizontal dunking results in a dunking time up to four times longer than traditional vertical dunking.

What's the reason for this? It seems that the answer is related to diffusion（扩散）, in other words, the length of time it takes for the liquid to penetrate the structure of the biscuit. Basically it takes longer for the liquid to travel through the channels of a biscuit when it is laid flat on the surface of liquid. Also the fact that when a biscuit is dunked horizontally, with the biscuit submerged in the liquid ,and the chocolate coating staying out of the liquid, the chocolate helps hold the biscuit together. Another factor influencing the equation is the temperature of the tea---the hotter the tea, the faster the sugar melts.

The researchers also found that by dunking a biscuit into tea or coffee, up to ten times more flavor is released than if the biscuit is eaten dry. So it's worth experimenting yourself. If you are wondering how you can perfect the horizontal dunk, the researchers have come up with an idea for a biscuit-holding device to make dunking biscuits easier. They are even now working on producing a table giving guidelines on dunking times for different types of biscuits. On that note, I think it's time to go off to the canteen for a tea break!

Part II

A: Hey, Louise! Look at this book about crop circles. Some of the photos

are absolutely unbelievable.

B: You don’t believe in all that stuff, do you, Peter?

A: I’m not saying I believe in UFOs and things. But some of the formations are fascinating. They’re made up of lots of the interconnected circles and geometrical shapes. You know, in the past few years, there have been more reports of then. The circles are getting larger and designs are getting more intricate. I’m sure that they can’t all be man-made. Think about it-they’re so complicated, and they appear night in the middle of fields of wheat, barley or corn. It’s definitely pretty weird.

B: I know, but I saw a TV documentary(纪录片)） about it. And they

showed how a group of hoaxers made an elaborate crop circle in the field at night. Using wooden planks, ropes, plastic tubes, and a garden roller. They even fooled some of the people who believe in the paranormal. Aliens coming down in UFOs and creating them and so on. A: I’m sure lots of them are created by people just to get publicity but look

here-it says ”The first records of crop circles get back as far as the 17th century. Since the 1917s, there have been of 12000 reports from countries all around the world, including Italy, America, South Africa, Australia and Brazil. Most reports are from here in England though. B: But surely that’s just because they get so much media coverage these

days? So more people are making them.

A: Perhaps. But how do you explain the fact that the actual chemical

composition of the grains of crops inside the circles changes? Scientific tests have found they have a higher protein level. The stems of the grains have often been exposed to high temperatures. And they found that the soil within the circles contains more iron than the soil outside. So far, the hoaxers haven't been able to copy all these features

B: Well, I’m not a scientist but I’m pretty sceptical about all these so-called

paranormal explanations. I remember in the programme I watched, the researchers found signs of human interference, such as holes in the earth and footprints. A: Come on, you must admit, that still leaves a lot which is unexplained! B: There’s lots of things that are hard to explain but this really.