〖TOEFL 2009上半年-Dark_Tournament听力组〗jy02885272 的听力备考日志贴

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March 26 2001-10-p4
Listen to a talk about enzymes in a biology class.
Let's begin today by discussing enzymes.
Enzymes are what make many of our bodies'biochemical recations possible.
Acturally biochemical recations can take placewithout them, but at much lower rates.
In fact the enzyme may cause a recation to proceedbillions of times faster than it would otherwise.
Before I go on to the biochemical specifics of howthis works, let me provide a figurative example.
I think it will helpillustrate the power of enzymes more clearly.
Now suppose you got abag, and you put a bunch(n.串，束，捆) oflocks in it, just small padlocks(n.挂锁).
Then you put in it all the keys that go with thelocks.
And you closed thebag and shook it hard. (shake-shook-shaken)
No matter how long you shook,chances are very small that any key would get inserted in any of the locks.
But if you took them all out of the bag and thistime used your hands to insert the keys in the locks, you could combine themmuch quicker.
Enzymes act like your hands, quickly allowing thebiochemical reactions that would otherwise take much longer.
Now there are two reasons that enzymes are soeffective at enabling biochemical reactions.
First, enzymes greatly reduced the amount ofenergy required to start the reactions and with less energy needed thereactions can proceed a lot faster than they could without the enzyme.
The second reason is that only a small amount of an enzyme is needed to enable the biochemicalreaction.
That' because the chemical structure of the enzymeitself does not become altered as it enables the action.
So a single enzyme can be used to start the samebiochemical reaction over and over again.

March 26 2001-10-p5
Listen to part of a lecture in an art historyclass.
Today I'd like to talk about the sculptor HenryMoore, in particular, the ideas in his work is based on and also how he viewed the medium of sculpture.
Moore said that to appreciate scupture, a personneeds to respond to form in all of its three dimensions.
He believed that this is more difficult thanresponding to art that is done on a flat surface, a surface such as canvas thathas only 2 dimensions.
For example, when you are looking at a painting,you don't have to walk around it.
You don't relate to form and shape in the same wayyou do when looking at a sculpture. Moore paid greater attention to shapes in nature, such as that of bones, shells and stones.
He thought that if you could appreciate the shapeof something simple like a stone, then you could go on to appreciate morecomplex forms.
He noticed that many of the stones he picked uphad holes in them.
One distinctive feature of Moore's scupture is hisuse of holes or openings to emphasize that he isindeed working in a 3-dimensional medium.
He believed that the shape of a hole itself couldhave as much meaning as that of a solid mass,and could even help creat a sence of mass or volume.
Moore was also interested in representing thehuman figure which he sculptured in suchmaterials as bronze, stone, and wood.
His sculptures of humans contained one person as in the work recliningfigure, or several people as in the sculpture family group.

March 26th 2002-01-p4
Listen to part of a talk in an astronomy class.
Today most astronomers accept the notion thatgroups of stars that make up the universe are all moving farther and fartheraway from each other.
But until fairly recently, this idea of expandinguniverse was not a theory most European scholars believed in, since ancienttimes, and up to about the 17th century.
Most of these scholars thought the size of theuniversize had remained unchanged since the moment of its creation, or perhapsforever, with all the stars remaining more or less in place in relation to eachother.
But this was chanllenged in the late 17th centuryby Issac Newton's idea of gravity as a force of attraction, which contradictsthe idea of a universe is stastic, unchanging.
If gravity causes all the stars out in? space to attract each other, as Newton said,then they couldn't remain essentially motionless.
Sooner or later all these stars would be falleninto one each other.
Well scientists then proposed a new model, takingNewton's theory into account, but they didn't want to abadon the idea ofmotionless stars, but for this model to work,
so the stars wouldn't fall in each other, they hadto modify Newton's law of graity, so they theorized that for distance as larges as those between stars, the gravition offorce repels rather than attracts.
As you might guess, this led to some othercontradictions.
But this were pretty well resolved in the pastcentury by the currently accepted theory, which says that the universe iscontinuously expanding.
You'll be reading about all of that for yourhomework tonight.

March 26th 2002-01-p5
Listen to a talk in a biology class.
On Monday we talked about insects and how theygather food.
Today I'd like to talk about the common gardenspider and how it captures its pray,
(would the round) net like structure it firstproduced almost 200 million years ago.
I mean of course a spider web.
What's interesting is why such a delicate structure isn't rippedapart when a fast-flying insect crashsinto it, and compared with the spider, theseinsects can be huge and really heavy.
In fact, capturing a large insect in a spider netcan be compared to (capture) catching an airplane in a fishingnet.
So how can the webabsorb such a shock without breaking?
Is it just because this silk like thread is made of so strong?
Well, experts analysed spider webs using a computer program, one designed (forcrashtesting cards...?), and they found that the structure of the web
the way the streads (were?) connected together helps balance the stresses(strength?) and tensions caused by the impact andspread them all across the web.
This saves the webs from being destroyed and bythe way suggests some creative new ideas that humans might use in designing
buildings.
The biggest surprise though is the role of air resistance in cushioning the shock of a collision.
The computer model showed that dragging a tiny threadfrom a spider web through the air is a lot likepulling a heavy rope through water.
And since air resistance acts on many threads all across the web, its amazingeffect are multiplied many times.
And this definitely helps the web survive theimpact.