托福听力是属于信息过量的题型，和阅读类似，会给出考生远超解题所需信息的素材内容，而考生除了基本的听懂素材里有什么信息外，也需要完成对听力信息的检查和价值判断的工作。下面小编就和大家分享托福听力中如何判断信息价值，来欣赏一下吧。

托福听力中如何判断信息价值

托福听力对话类conversation素材信息如何判断?

托福听力从给出素材的类型来说主要可以分为对话conversation和讲座lecture两种，我们先来说说对话类素材中的信息价值判断方法。

按照对话conversation中常会给出的题目和其文本形式来看，每一段对话中，提问一方问的是什么问题其实并不重要，相对来说回答这个问题的答案中才会包含比较多的有价值的解题信息。而在回答的答案部分里，一开始的那一段对于之前问题的直接回答也就是回答者的观点更为重要，而跟在观点之后的很可能是一些类似于论述举例解释的内容，这些内容的价值其实就没有那么高了。另外，对话中并不是每一个问题加回答都需要关注，那些提问比较明显，一般直接用what, when ,where, why等提问词的问题的解答才更重要，其它一些提问不明显，回答也只是起到确认作用的内容多半没有什么价值，也不会成为提问点。最后，关于之前提到的回答者的观点，也并不是全部都要记的，如果回答者自身观点不够明确，其中包含了诸如sometimes或是maybe这样不确定语气态度的词汇，那么这个回答的观点价值也是比较有限的，大多数只是对听力素材中主要观点的补充。

托福听力讲座类lecture材料信息价值判断心得

比起之前的conversation，讲座lecture可能是考生更难以判断和把握信息价值的素材类型，因为讲座中包含的信息线索只会更多更复杂，考官的出题点也更难以判断。仅从托福官方给出的信息来看，讲座类听力素材包含了46个不同学科话题的相关内容，涉及到的话题范围实在太过广泛。另外其展现形式也不同于对话这样有来有回的回合制形式能够明显看出一问一答，而是通篇平铺直叙，因此考生判断信息价值的难度也大幅提升了。

因此，对于讲座类听力素材，小编建议大家获取信息点的方式主要以抓敏感词和整理讲座内容整体结构为主，在此基础上再尽可能多的记录各类细节，争取踩到提问点以满足解题需求。具体来说，大家先要以最快的速度第一时间搞清楚讲座的话题主题，之后根据讲座进行过程中主讲者给出的各种线索类词汇，比如today后面一般就是这次讲座的主要观点，然后first, second之类大多是分论点等等。具体的关键词汇大家可以通过实际的lecture素材来整理，每个人对不同关键词的敏感度都不同，所以需要自己归纳总结才会更有效果。另外对于讲座类听力素材比较常见的出题点也需要考生在做题过程中多加关注，不要只顾着做题，而是多分析一下为什么会在这里出题。通过这种考试，考生对于托福听力讲座类素材的信息价值，才能有更为准确的判断。

2020托福听力练习：珊瑚漂白现象阻碍鱼类学习躲避捕食者

In April the world learned that more than 90 percent of Australia's Great Barrier Reef had become bleached. That is, warming waters or other conditions cause the algae living in the coral to exit, leaving the coral weak. It's a bleak statistic, because it's reasonable to assume that as the corals themselves suffer, the entire ecosystem they support suffers as well.

For example, a study finds that bleaching hinders fish from learning to avoid predators.

Imagine you're a fish, and suddenly one of your friends meets its unfortunate end in the jaws of a predator.

"We found that these animals actually have this really sophisticated way of learning, which involves the linking of chemical alarm cues, which are damage-released cues from conspecifics, and any other smell or even the sight of anything novel... sort of a Pavlov's dog-type scenario."

James Cook University marine scientist Mark McCormick. He and his team found that this learning process breaks down when the coral becomes bleached. Instead of hosting algae within, the bleached coral becomes blanketed by algae.

"We've used little patches of live coral and little patches of dead and degrading coral, which have similar topographic complexity, and what we've done is we put those little patches within a bed of either live coral or dead and degraded coral."

Onto each patch, the researchers deposited a small, naive reef dweller called a damselfish. They wanted to see how the health of the reef influenced the fish’s ability to learn to avoid the odor of a predator called the dusky dottyback. And they found that the presence of degraded coral—even if surrounded by a healthy reef—entirely disrupted that learning mechanism.

"It touches on a really big issue, to some extent a really global issue. So, even though this is actually dealing with a relatively small aquarium fish, it's got life history traits that are very similar to virtually all of the other marine organisms."

So, is there anything that can be done to help the world's reefs and their inhabitants?

"These communities are going to have to try and rebuild, and they have really effective mechanisms whereby they can re-seed themselves. But we're talking about timescales of really probably 10-15 years to actually get a healthy reef back after really a cataclysmic change."

And for that to happen, McCormick says, we need to reduce our CO2 emissions and to stop polluting our waterways. In order for things to improve underwater down under.

Thanks for a minute for Scientific American — 60-Second Science. I’m Jason Goldman.

今年4月，全世界知道了澳大利亚大堡礁有超过90%的珊瑚出现漂白现象的消息。这是由于温暖的海水和其他条件导致珊瑚排出了共生的藻类，这使珊瑚变得虚弱。这一数字并不乐观，因为我们有理由认为在珊瑚本身遭受破坏的同时，支持珊瑚的整个生态系统同样遭到了破坏。

举例来说，一项研究发现，漂白现象对鱼类学习躲避捕食者造成了阻碍。

想象一下，假如你是一只鱼，突然你的一个同伴遭遇不幸，命丧捕食者口中。

“我们发现，这些动物的学习方式非常复杂，学习过程包括与化学物质相关的警报提示，即同种生物传递出的危险信号和味道，甚至是不同寻常的景象，就像巴甫洛夫的狗这种理论。”

这是詹姆斯·库克大学的海洋科学家马克·麦考密克所说。他和他的团队发现，在珊瑚漂白化以后，这种学习过程就被破坏了。藻类不再生活在珊瑚体内，而是会覆盖住珊瑚。

“我们用小块活珊瑚和死后降解的珊瑚进行了实验，它们拥有类似的地形复杂性，我们把这些小块珊瑚放在有活珊瑚或死后降解珊瑚的海底。”

研究人员在每块珊瑚上放了一个小“礁民”——雀鲷。他们想知道珊瑚礁的健康如何影响鱼类学习躲避捕食者气味的能力。他们发现，降解珊瑚即使处在健康的珊瑚礁中，也会彻底破坏鱼类的学习机制。

“这涉及一个非常重要的问题，从某种程度上可以说是全球问题。虽然这只是用相对较小的水族观赏鱼进行的实验，但是实验得出的生活史特征和所有其他海洋生物类似。”

有没有什么方法能帮助世界上的珊瑚礁和栖息于珊瑚礁的生物?

“这一群体需要重建，它们拥有可以自我修复的高效机制。但是在灾难性变化之后，这些珊瑚恐怕需要10年至15年的时间才能恢复正常。”

麦考密克表示，为了让珊瑚恢复健康，我们要减少二氧化碳排放量，停止污染水域的行为。这样才能保证海底的情况得到改善。

谢谢大家收听科学美国人——60秒科学。我是杰森·高曼。

重点讲解：

1. break down 出毛病，损坏;

例句：Her health broke down under the pressure of work.

工作的压力把她的身体弄垮了。

2. touch on 谈及;涉及;

例句：The book does not touch on this question.

这个问题书里面没涉及到。

3. to some extent 在某种程度上;

例句：To some extent I hold that opinion of them still.

在某种程度上，我仍对他们持同样的看法。

4. be similar to 相像的;相仿的;类似的;

例句：His stance towards the story is quite similar to ours.

他对该报道的态度和我们很相像。

2020托福听力练习：黑洞碰撞合并对引力波影响

The news last month that gravitational waves had been discovered made waves throughout the world of science.

The finding, from the Laser Interferometer Gravitational-Wave Observatory, or LIGO, showed that extreme gravity can cause ripples in spacetime.

In the case studied, the extreme gravity came from two colliding black holes.

Now one scientist is suggesting an added wrinkle—that those two black holes might have originated in a single star.

“The situation is similar to a pregnant woman that has twin babies in her belly.”

Avi Loeb of the Harvard-Smithsonian Center for Astrophysics.

He's proposing the idea in a paper that's been accepted for publication in the Astrophysical Journal Letters.

Loeb became suspicious because just 0.4 seconds after LIGO spotted the gravitational waves, a space telescope called Fermi glimpsed a bright flash of gamma-ray light in the same area of the sky.

“Detecting such a signal is quite surprising from a collision of two black holes.

What could be the source of a flash of light following a black hole merger?”

Colliding black holes should not produce such light—but the death of a very massive star could.

“My idea was that if the star is spinning very rapidly to start with, then as its core collapses it produces a bar that breaks into two clumps of matter, sort of like a dumbbell configuration. And these two clumps of matter orbit a common center, and they eventually collapse independently into two black holes.”

Of course, it's possible that the Fermi telescope signal was a false alarm.

So we'll see if future gravitational wave detections are also accompanied by flashes of light—supporting the idea that twin black holes collided upon the collapse of a massive star.

上个月人类首次直接探测到引力波的新闻在科学界激起了波澜。

这一在激光干涉引力波天文台(LIGO)上的重大发现,表明极限重力可以引发时空涟漪。

在这项研究中,这种极限重力来自两个黑洞的碰撞。

美国宇航局费米太空望远镜在引力波信号之后大约0.4秒检测到伽玛射线爆发.jpg

而现在一位科学家提出一种特别的理论，那就是这两个黑洞可能起源于同一颗恒星。

“这样的情况就好比一位怀有双胞胎的孕妇一样。

“哈佛-史密森天体物理中心的天体物理学家艾维·勒布说道。

在《天体物理学杂志》上发表的一篇研究中他提出了这样的观点。

勒布提出质疑是因为LIGO观测到引力波信号仅0.4秒后,费米太空望远镜就检测到伽玛射线爆发，而引力波和伽玛射线爆发均产生于同一片区域。

ab两图是通过数值求解爱因斯坦方程得到的双黑洞轨道演化.jpg

“检测这样一种来自两个黑洞碰撞的信号令人非常吃惊。

黑洞碰撞合并后闪光可能的来源是什么?”

碰撞的黑洞不应该产生这样的光芒，但一颗大质量恒星死亡后却可以。

“我的设想是,如果恒星的转速足够快，它的核心将伸展并呈现哑铃状，随后分裂为两个部分，每个部分单独形成一个黑洞。

当然,也存在费米太空望远镜所检测到的信号是一次假警报的可能。

因此如果未来的引力波探测也伴随闪光，支持两个黑洞相撞可能来自于一颗大质量恒星消亡的产物，我们将对此拭目以待。

1.gravitational wave 引力波

例句:What will happen when a gravitational wave was found by my computer?

如果一个引力波被我的电脑找到了(计算出来了)，会怎么样?

2.come from 来自

例句:I come from the north.

我是北方人。

3.black hole 黑洞

例句:Radio signals received from the galaxy's centre back up the black hole theory.

从该星系中心收到的无线电信号证实了黑洞理论。

4.start with 开始

例句:To work out a plan, one has to start with investigation.

制定计划要从调查研究入手。