为什么托福听力会听不懂素材内容?这3个主要原因需了解
托福听力听不懂原因：单词听不懂
单词不认识其实是众多托福考生的硬伤，试想一个从来就没见过的单词，就算听上一千一万遍也不可能把意思给凭空悟出来。而对于一门语言类考试而言，不背单词想考过的念头更是不切实际。很多同学都会抱怨，托福单词太多太难，背不下来或者背了也会忘。那么首先，对于新托福听力来说，虽然涉及到众多专业的学科性的内容，但考试的实质依旧是语言而不是专业知识，因此，单词不需要一开始就记太偏太难的，先从最基本的开始。另外，大多数考生对于单词识记的方法也有问题，听力强调用耳朵识别单词，从而知道其意思。很多同学对于单词只认识其写法和意思，不关注读法的背诵方式，势必在听力中造成单词看得懂，听不懂的情况。这样在真正的考试当中，单词无法用耳朵识别出来，看起来再熟悉也无济于事了。
托福听力听不懂原因：惯用说法听不懂
由于新托福听力取材真实的校园生活学习场景，所以其中的语言也很生活化，更加鲜活。这些内容对于绝大部分考生来说都很陌生，因为传统的中国英语教学中学习到的都是过于正式或者老套的说法。很多同学都没有在意这点，甚至在出国了以后，最基本的打招呼问好都要花好久才能适应，因为课本上学的打招呼的方式是”How are you?” 或者”How do you do?” 当听到外国人以平常语速说出”How is it going?” 或者”How are you doing?” 的时候，肯定不知道别人在说什么，更不用说怎么回应了。类似的情况在新托福听力当中比比皆是。当然，就应对托福考试来说，可以先把听力文章中鲜活的用语学会，如果能配合一些电影或者美剧，多进行了解巩固，那效果肯定更好。
托福听力听不懂原因：言下之意听不懂
在新托福听力考试当中，不仅有直接考细节信息的题目，也会有考对于字面意思理解的题目，说白了，就是考某句话的深层含义。这样的题目是在中国大多数英语考试当中没有的，因此很多考生会觉得很不适应，但其实这样的题目仅仅是纸老虎。
例如：
一学生在办公室问学校工作人员”I am supposed to be having my class right now, but I can’t find my classroom, do you know where it is?”
而工作人员答道”There is a room assignment sheet on the bulletin board outside this office.”
在新托福考试中，对于后一句话，就会提问工作人员说这句话是什么意思。这样的题目的难点在于，在听懂字面意思的情况下，需要通过对于上下文的理解，知道说这句话的真正目的，意图。比如在这里，我们听到上文学生在问教室在哪时，就应该推测到下文应该是对学生问题的一个回答，虽然字面意思是”办公室外的公告栏上有教室分配表”，但目的不在于说哪有个什么东西，其实意图是告诉学生，你自己去看分配表，找自己的教室在哪，即回答学生”教室在哪”的问题。对于此类题目，考生们要摒弃只考虑单个句子意思的习惯，逐渐培养自己在听懂的情况下思考上下内容的联系，思考文字以下更深层的内容。
对于托福听力听不懂的原因小编就为大家分析到这里，希望考生能够寻找到自己托福听力听不懂的原因，并找到应对方法尽早解决，如此才能在托福考试中拿到理想的听力分数。
2020托福听力练习：蛋白质测试补充DNA分析
DNA analysis is a staple of crime scenes—and crime shows, like HBO's The Night of or the old standby, CSI:
"We just need to get this to the DNA lab, confirm it's the victim's blood. And then, case closed."
And it's not just for crime: DNA sequencing also helps determine our relationship to Neandertals, and our primate cousins.
Problem is, DNA's a relatively fragile molecule—it doesn't last forever. What's more sturdy is protein. So now researchers have come up with a way to use protein in a similar way to DNA: to link an individual to a piece of evidence or to determine ethnic background.
The protein source these scientists studied was human hair, from 76 individuals of European-American, African-American and Kenyan descent. And they determined that the variation of a couple hundred proteins in a person's hair could be enough to single her out from a group of one million individuals.
The way it works is that proteins are made according to the instructions in DNA. So one individual's genetic variations can result in slightly different proteins being made, compared to another individual. And by determining the protein composition, the scientists can then extrapolate info about the DNA. The results are in the journal PLoS ONE.
The researchers say the technique still is not ready for prime-time—ideally the process needs to be more sensitive, to avoid consuming valuable crime scene or archaeological samples in the analysis. And the statistics behind the technique need to be validated, too. But someday, they say, it could come within a hair of DNA analysis.
DNA分析是犯罪现场和犯罪片采用的主要方法，就像家庭影院频道(HBO)的电视剧《罪恶之夜》和老牌美剧《犯罪现场调查》中经常出现的场面。
“我们只需要将这个送到DNA实验室，确认这是受害者的血迹。然后就可以结案了。”
但是，DNA分析不仅仅只是用于犯罪调查，DNA序列还可以帮助确定我们与尼恩特人以及与灵长类动物的关系。
问题是，DNA是一个相对脆弱的分子，其并不会永远存在。更加坚固的是蛋白质。所以现在研究人员提出了一种利用蛋白质的新方法，该种方法与DNA的使用方法非常相似：将个体同证据联系起来，或是确定种族背景。
这些科学家研究的蛋白质来自人类的头发，这些头发采集自欧裔美国人、非洲裔美国人以及肯尼亚的76个个体。科学家发现，一个人头发中数百个蛋白质的变化足以将该个体与其他100百万个个体相区分。
这种方法就是根据DNA的指令来操作蛋白质。所以，与其他个体相比较，一个个体的基因变异会产生略有不同的蛋白质。通过确定蛋白质的组成，科学家可以推断出DNA的信息。这项研究结果发表在《公共科学图书馆·综合》杂志上。
研究人员表示，这项技术尚未成熟，在理想情况下，该过程需要更加的谨慎，以避免在分析中浪费宝贵的犯现场或其他考古样本。另外，该技术的支持数据也还需要验证。但是，科学家表示，有朝一日可以实现通过头发来验证DNA。
重点讲解：
1. come up with 想出，提出(计划、想法等);
例句：I had a hard time trying to come up with an idea.
为了想出主意我苦思了半天。
2. single out 单独挑出;特别选出;
例句：He was singled out for special training.
他被选拨出来接受专门训练。
3. according to 依据，根据，依照 (原则等);
例句：He ranged the books according to size.
他照大小顺序排列这些书。
4. result in 导致;引起;造成;
例句：It resulted in a diminished output.
这导致了减产。
5. compared to 与…相比;和…比起来;
例句：The cost is just peanuts compared to what you get from the money.
和你投资所获得的利益相比，这点成本就不算什么。
2020托福听力练习：鲨鱼体内含毒素或威胁类
Living at the top of the food chain, sharks can accumulate dangerous levels of methylmercury. So much that pregnant women and children are advised not to eat shark at all. But sharks can accumulate another toxin too, called BMAA, which has been linked to the development of neurodegenerative disease. Which could be bad news for shark eaters.
"Mercury in combination with BMAA is a one-two punch." Deborah Mash, a professor of neurology at the University of Miami's Miller School of Medicine. "These are two synergistic toxins. So even if there are low levels of exposure from the mercury or the BMAA, when humans are exposed to both of these toxins, then they will have a synergistic effect on the nervous system."
BMAA starts out in cyanobacteria, and travels up the food chain through crabs and shrimp and fish. And, as previous studies have shown, makes all the way to sharks. What Mash and her colleagues wanted to know was how widespread the problem was, and if the chemical often appeared alongside mercury. So they analyzed fin and muscle samples from 10 species of shark—55 individuals in all—from the Atlantic and Pacific Oceans. And they found BMAA and mercury in all 10 species. Suggesting that exposure to that "one-two punch" could be pretty common. The results are in the journal Toxins.
It's still not clear at this point what sort of risk this occasional exposure through food might have. Still, Mash isn't waiting.
"I myself would not want to be exposed to BMAA or methyl mercury in my diet by eating shark fin or shark meat or taking shark cartilage products. We already know that mercury is toxic to our health. And we already know that BMAA plus mercury is a very bad mix for the brain. So people need to be concerned, and I think that's not only for the benefit of us as consumers, but also to the poor sharks, who are threatened with extinction."
Conservationists have argued for years that sharks should be spared. Maybe now that it's us who are threatened… people might finally start to leave them alone.
因为生活在食物链的顶端，所以鲨鱼可以积累达到危险水平的汞。因为鲨鱼体内的汞含量非常高，所以建议孕妇和儿童不要吃鲨鱼。但是，鲨鱼还能积累另外一种毒素——BMAA，这种毒素与神经退行性疾病的发展有关。这对爱吃鲨鱼的人来说可是个坏消息。
“汞和BMAA的结合可谓是双重重击。”黛博拉·马许是迈阿密大学米勒医学院的神经学教授。“这是两种协同作用的毒素。即使汞或者BMAA的含量很低，但是只要人类接触到这两种毒素，它们就会对人的神经系统产生协同效应。”
BMAA最初存在于蓝藻中，之后通过螃蟹、虾类和鱼类进入食物链上层。此前的研究已经表明，BMAA最后进入鲨鱼体内。马许和她的同事们想知道，如果这种化学物质经常和汞一起出现，那这个问题的普遍性有多大。所以，他们从太平洋和大西洋的55只鲨鱼中提取分析了10种鲨鱼的鳍和肌肉样本。在这10种鲨鱼中，均发现了BMAA和汞。这表明，这两种毒素的结合非常普遍。该研究结果发表在《毒素》杂志上。
目前尚不清楚通过食物接触这些毒素会产生何种风险。但是马许并没有坐等结果。
“我不想因为吃鱼翅、鲨鱼肉或服用鲨鱼软骨制品而在饮食中接触到BMAA或甲基汞。我们已经知道汞危害我们的健康。我们也知道BMAA和汞结合会对我们的大脑造成更严重的危害。所以，我认为人们担心的不应该仅仅是我们作为消费者的利益，同时也要担心濒临灭绝的可怜的鲨鱼。”
多年来，环保人士一直认为应该保护鲨鱼。也许现在受到威胁的是我们人类……所以，现在人们可能不会再去管它们了。
重点讲解：
1. even if 即使;尽管;纵然;
例句：They'll stand by you even if you don't succeed.
即使你不成功他们也会支持你。
2. be exposed to 使暴露于(险境);使遭受(危险或不快);
例句：Women who are exposed to mercury, cadmium, or vinyl chloride before conceiving seem to be especially likely to have autistic kids.
女性在怀孕期间接触汞、镉或氯乙烯很有可能会生出自闭症患儿。
3. start out 起初是…;
例句：He started out to fix the car himself, but in the end, he had to ask for help.
起初他本打算自己修车，可最后他还是不得不请人帮忙。
4. leave alone 听…自便;随…去;不打扰;
例句：Some people need to confront a traumatic past; others find it better to leave it alone.
有人需要直面过去的创伤，有人则觉得不去想它为妙。
