Prática de Shadowing: The only good nuclear accident - Aprenda a falar inglês com vídeo
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Put on your guns.
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There's something really unusual about this photo from 1955.
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Can you spot it?
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It was taken on Fremont Street in Las Vegas.
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And this glow from the side is the only indication that the photographer had captured the explosion of an atomic bomb.
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Three, two, one.
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After World War II, the U .S detonated dozens of test nukes at a site an hour outside Vegas.
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These weren't little explosions.
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Many were as large as the blast that killed 140 ,000 people at Hiroshima.
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On Pacific Islands, they tested the much more powerful hydrogen bombs.
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But it was the Soviets who dropped the largest nuclear weapon ever tested.
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Before 1963, above -ground nuclear tests released the explosive power of 25 ,000 Hiroshima bombs, with lasting effects on communities nearby.
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But the reason we're talking about this today is that those mushroom clouds also created a new scientific tool,
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one that could reveal whether this painting is a forgery or how long this shark could live, or if selling this ivory figurine was a violation of international law.
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We are going to dig into this mystery, and you'll see how nukes from the Cold War became a weapon in the fight against the slaughter of elephants.
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This statue of a poet with a basket of peonies was
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one of 76 ivory artifacts seized from the home of an antiques dealer in the Czech Republic.
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He'd told the authorities that he'd inherited the artifacts from his mother and that they were legal to sell.
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But were they?
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That depends on exactly how old that ivory was.
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Ivory comes from the teeth of certain animals, most often the massive upper incisors of the elephant.
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They grow these tusks for foraging and fighting.
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But humans realized a long time ago that they also make great art supplies.
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Ivory is a really beautiful material.
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It's shiny and smooth and dense.
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Across different cultures and centuries, ivory has been moved around the world to be carved into art for the elite.
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And later, to be fed into machines to make products for the middle class too.
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The tusks took increasingly remote journeys from their source at times carried by people who were enslaved.
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And by the 1980s, after Japan became the world's top ivory importer, elephant populations were in free fall.
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So governments got together and banned the international trade in ivory that had been operating for thousands of years, leaving some exceptions for antique artifacts.
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When the ivory ban happened in 1989, they completely shut down poaching.
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But it was not very long -lived, maybe three, four years, and then poaching started to creep up again.
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By one estimate, 144 ,000 African elephants were killed between 2007 and 2014 as demand picked up in China.
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Poaching has declined some since then, but African elephants are still endangered because people are still buying and selling illegal ivory.
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And just a quick break to say that this footage came from Storyblocks, which is the sponsor of today's video.
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We love Storyblocks.
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Storyblocks is this huge library.
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It's all available if you have a subscription, so you don't have to pay individually for different clips.
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And one thing that's happening is that stock libraries are starting to fill up with AI -generated stuff.
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But Storyblocks recently put out a statement.
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I want to read it to you because I thought it was really interesting.
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They said, while we see practical use cases for generative AI video, audio, and images, we do not accept generative content submissions into our library.
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What a relief.
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Yeah.
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For us, when we're trying to make journalistic content and say, look at this thing that's real out in the world, it's nice to know that we can still do that with Storyblocks.
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Right now, you can get two extra months free when you sign up for their annual plan.
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Go to storyblocks .com slash howtown to grab that offer before it's gone.
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Okay, let's get back to this guy.
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The dealer who was selling it had a report from a specialist in East Asian culture who said
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that the artifacts came from the first Chinese republic before 1947.
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That would make them legal to sell under the EU's rules at that time.
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But a team of researchers in the Czech Republic decided to fact -check that expert with a more objective test,
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a test that relies entirely on those nuclear bombs from the 50s and 60s.
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And what was that test?
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Well, what do you know about carbon -14?
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I know that carbon, so carbon -12 is the most abundant one.
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Carbon -14, I believe, has two extra neutrons kind of stuck on there.
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Is that right?
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That's right.
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Carbon -14 is an isotope of carbon, but it comes from nitrogen.
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Almost 80 % of Earth's atmosphere is composed of nitrogen atoms, which have seven protons and seven neutrons.
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But if a spare neutron passes close by, a nitrogen nucleus can absorb it, creating an excited form of nitrogen -15,
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which quickly relaxes by releasing a proton.
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That turns it into carbon, carbon -14, otherwise known as radiocarbon, which reacts with oxygen to produce a special,
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limited -edition form of CO2.
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But all you really need to know is that those spare neutrons
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that kick off that whole process can come from natural sources, or they can come from nuclear bombs,
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which completely altered the ratio of carbon 14
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and carbon 12 in the air i'm curious how much variation
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it has had sort of naturally compared to the bomb pulse
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if you look at what has happened in the last 5 000 years we're of the order of few percent
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but if you compare it with the bomb spike you know the radio carbon concentration doubled between 1955 to 1963
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so in just eight years which is nothing in the history of our planet, it's very, very...
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Unmistakable.
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Yeah, that's for sure, yes.
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A 1963 treaty required nuclear tests to be done underground, so the concentration of carbon -14 in the air peaked
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and then declined as the carbon cycle moved the CO2 into the oceans and into plants through photosynthesis.
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Researchers quickly detected the spike in twigs from Rome, in the milk of cows in Norway, and after a lag of about a year in the blood of New Yorkers.
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They've been tracking the carbon -14 in the air ever since, and when you compile the data from the past 60 years, we get the radiocarbon bomb curve.
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This is more than just an odd souvenir from the Cold War
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because the bomb pulse installed a clock in every living thing.
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So what year were you born?
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1987. Okay, so the enamel of your molars, which formed around the time you were born, captured the air around 1987.
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Right.
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Part of the lens in our eyes also locks in carbon around birth, so that's another neat archive.
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A little less accessible, though.
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Unfortunately, yeah.
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And then your bones turn over more slowly.
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So right now your rib reflects the air from about 10 or 20 years ago.
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and then the carbon in your hair
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and your nails changed over within the last three years
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and those keep updating until you die nice
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if i don't know anything about when you lived
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but i for some reason have some of your teeth
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and some of your hair i can put your life on a timeline plus
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or minus a few years thanks to the bomb pulse i guess you're looking at my corpse in this macabre example.
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I'm sorry I used you for an example.
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Yeah, what is this?
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I should add that radiocarbon takes a slower route from the air through the ocean.
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So if someone eats mostly seafood, their bodies will contain carbon from an older atmosphere, and you have to adjust for that.
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You start with physics and then you end up with biology, biochemistry, and mathematics as well.
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So it's interesting.
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Most of the nuclear tests were done in the northern hemisphere.
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But carbon mixes globally in the air after a couple of years.
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So all of the elephants that have lived since the 1950s have teeth that were time -stamped with the bomb pulse.
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That makes it a unique tool for tracking the ivory trade.
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The researchers carefully drilled out a sample from the bottom of the statue and measured the concentration of carbon -14.
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And they found that it matched the atmospheric level after the start of the nuclear tests, not before.
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Same with this one, and this one, and this one.
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In their study of 46 artifacts from multiple seizures, the Czech researchers concluded that nearly 60 % were not legal antiques,
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contradicting the experts who had said they were.
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The dealers were convicted and punished for marketing ivory that was harvested after 1947.
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But the study couldn't tell us exactly how recent that ivory was.
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That's because the bomb pulse offers two possible dates for a given level of carbon -14, in this case 1962 and 1974.
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To figure out which one is correct, they would need to drill another hole in the statue.
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See, an elephant's tusk grows continuously from a cone of tissue at the base called the pulp cavity.
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So the tip captures carbon that the animal consumed at the beginning of its life, and the base captures the carbon around the time of death.
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If I can take two samples, one closer to the tip and the other one closer to the base.
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Then I know that regardless of the age I measure, the sample which is closer to the tip has to be older than the one closer to the base.
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And so I can exclude all the possible time intervals which do not respect this relative dating.
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Somehow you have to be clever. So clever.
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You could also compare the ivory at the center of a tusk to the outer layers which are older.
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That's what they did in this study of raw ivory that had been seized by authorities in multiple countries.
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They had the base of the tusk so they could take a sample right along the pulp cavity, the ivory that formed just before death.
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So we wanted to see, well, how recently were these animals killed relative to the time their ivory was seized?
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And we were shocked to find that the vast majority,
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literally almost all, the ivory for savannah elephants were killed within two years of the time their ivory was seized
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and for forest elephants within three years of the time their ivory was seized.
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But in a follow -up study of more recent seizures, Sam and his colleagues found nine tusks that dated back to the 1980s.
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It seemed that they had been stolen or sold out of a government stockpile in Burundi, where they were supposed to be locked up for good.
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Scientific discovery is unpredictable and opportunistic.
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It sprouts from whatever puddles of data it can get.
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And it can get less than we often assume.
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Without the nuclear escalation of the Cold War, we wouldn't have a way to date elephant ivory from the 20th century.
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Bomb carbon has also been pulled from canvas and paint to catch forgeries, from wine and whiskey to fact -check their vintage,
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from the eye of a Greenland shark to confirm its remarkable lifespan ban.
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It has helped Gianluca determine whether unmarked graves in Cyprus came from violent conflicts in the 60s and 70s.
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More than 2 ,000 persons simply disappeared.
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Of course they were killed.
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And in some cases they could really find,
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identify the person, name, and return the rest to families for a proper burial.
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And it's very touching.
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But at some point in the last few years, carbon -14 returned to its pre -bomb ratio in the air.
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And that has happened faster than it would have if we weren't diluting the signal by burning fossil fuels, which contain carbon -12 but not carbon -14.
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It's just a weird quirk of history that we're in this perfect period where the bomb pulse is a useful tool.
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Yeah, and it's over.
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hey wait
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but how is bomb pulse dating different from traditional radiocarbon dating
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i'm going to explain this really quick we'll make this a bonus video
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that anyone can watch for free by joining our patreon okay so this show
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Vocabulário e dicas de fala para esta lição
Este vídeo tem 150 frases e 2027 palavras para praticar shadowing. A fala dura 12:53. O falante fala em ritmo natural, cerca de 157 palavras por minuto, próximo de uma conversa do dia a dia. Apenas 80% das palavras estão entre as 3.000 mais comuns do inglês, por isso o vocabulário é exigente.
Vocabulário principal deste vídeo
15 palavras do vídeo que vale a pena aprender, com pronúncia e significado:
| Palavra | Pronúncia | Significado |
|---|---|---|
| ivory substantivo | /ˈaɪv(ə)ɹi/ | marfim, ebúrneo |
| elephant substantivo | /ˈɛlɪfənt/ | elefante, elefanta |
| pulse substantivo | /pʌls/ | pulso |
| seize verbo | /ˈsiːz/ | agarrar, capturar |
| capture verbo | /ˈkæp.(t)ʃɚ/ | capturar |
| researcher substantivo | /ˈɹiˌsɝ.t͡ʃɚ/ | pesquisador, pesquisadora |
| nitrogen substantivo | /ˈnaɪ.tɹə.d͡ʒən/ | azoto, nitrogênio |
| concentration substantivo | /ˌkɑn.sənˈtɹeɪ.ʃən/ | concentração |
| dealer substantivo | /ˈdiːlə(ɹ)/ | negociante |
| statue substantivo | /ˈstæt͡ʃu/ | estátua |
| antique adjetivo | /ˌanˈtiːk/ | antigo, antiquado |
| relative substantivo | /ˈɹɛl.ə.tɪv/ | parente, parenta |
| atmosphere substantivo | /ˈætməsˌfɪɹ/ | atmosfera |
| compare verbo | /kəmˈpɛɚ/ | comparar |
| decline verbo | /dɪˈklaɪn/ | declinar |
Phrasal verbs que você vai ouvir
| Palavra | Significado |
|---|---|
| figure out verbo | descobrir, deduzir |
| get together verbo | reunir |
| put out verbo | colocar/botar/pôr para fora |
| shut down verbo | apagar, encerrar |
| turn over verbo | inverter |
Pronúncia para ficar de olho
O falante usa 19 contrações e formas reduzidas, como we're, I'm, don't. Diga-as na forma curta, do jeito que você ouve.
- Os sons de “th”: smooth /smuːð/, mathematics /mæθ(.ə)ˈmæt.ɪks/
- Os sons de “sh” e “zh”: capture /ˈkæp.(t)ʃɚ/, concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, ratio /ˈɹeɪ.ʃoʊ/, explosion /ɛkˈsploʊ.ʒən/, seizure /ˈsi.ʒɚ/
- Palavras longas — acerte a sílaba tônica: concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, naturally /ˈnæt͡ʃ.(ə.)ɹə.li/, unusual /ʌnˈjuːʒ(u)əl/, photographer /fəˈtɑ.ɡɹə.fɚ/, biology /baɪˈɑ.lə.d͡ʒi/
Como praticar com este vídeo
- Ouça o vídeo inteiro uma vez sem falar e anote as palavras que você não conhece.
- Comece na velocidade 0,75×, faça shadowing frase por frase e volte à velocidade normal quando ficar fácil.
- Grave a sua voz e compare com o original, prestando atenção a palavras como ivory, elephant, pulse.
Gramática neste vídeo
As estruturas que o falante mais usa, com as palavras exatas do vídeo:
| Estrutura | No vídeo |
|---|---|
| Voz passiva be + particípio passado — o foco está no que acontece, não em quem faz | was taken · has been moved · be fed |
| Present perfect have/has + particípio passado — uma ação passada que ainda importa agora | has been moved · has declined · has happened |
| Orações relativas who / which + oração — informação extra sobre uma pessoa ou coisa | people who were · Storyblocks, which is · atoms, which have |
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.