Placeholder Image

字幕列表 影片播放

  • from the waters in the Yangtze River in China

  • rises the biggest concrete structure a plan

  • the Three Gorges Dam is over two kilometers long

  • and 60 stories tool

  • it has taken forty thousand workers over 70 years to build

  • when it fully comes online this one down

  • will produce over 20,000 megawatts how

  • twice as much as cool the nuclear power stations in Britain put together

  • it is the pinnacle damn engineering

  • home the Three Gorges Dam

  • owes its success to 5 landmark times

  • in the heart it leaves lies a major technological innovation

  • allowed engineers to build and big data

  • one by one traveling up the scale will reveal the incredible stories behind

  • the structure

  • on

  • and the inventions that allowed them to produce

  • evermore power

  • 6 ingeniously forward from being

  • to bigger into the world

  • things

  • I'm

  • here I'm

  • them

  • I'm

  • China is one fastest-growing economies on

  • to fuel the need to mix ever accelerating industry nation needs more

  • much in this would be provided by an enormous

  • down spanning the mighty Yangtze River in central China

  • called the Three Gorges

  • our cameras have been granted privileged

  • access to capture this amazing feat of engineering

  • in its full glory

  • the

  • before they could start building 3 largest the Chinese first had to divert

  • the Yangtze

  • River which is almost two kilometers wide and move

  • over a million people from the area about to be flood

  • Three Gorges Dam is the biggest hydro-electric project in the world

  • this damn news 28 million cubic meters a cock maybe one way to look who's to say

  • saw solid hyper concrete a meter diameter

  • right around the world lot a concrete

  • the chinese authorities think it's worth the effort as the Three Gorges Dam will

  • provide clean

  • and cheap electric power to millions

  • to understand how the Three Gorges Dam can produce so much

  • we need to travel back in time

  • to nineteenth-century Britain

  • and a modest stream in Northumberland the power behind the world's

  • first hydroelectric dam

  • in the eighteen hundreds while Britain is at the heart of the Industrial

  • Revolution

  • this house is the last word in modern lived

  • it belongs to Lord Armstrong an entrepreneur

  • and obsessive invent he has fitted his house with state-of-the-art technology

  • including central heating and mechanical devices that drive elevators

  • laundry machines and roasting space

  • but there is one place in the house where modern technology

  • is sadly lacking as historian and Tony Burke

  • explains this was Armstrong's

  • real pride and joy the picture gallery for wonderful Victorian paintings

  • bit gloomy even in daylight what he really wanted to do

  • was to bring his guests here in the evening by the flicker candle light

  • nothing really worked

  • what Armstrong needs

  • our electric lights and away to power them

  • how do you generate electricity that something was known for

  • fifty years was Michael Faraday a given the secret you move

  • a magnet in relation to call on work bundle set appear

  • so how it might work now

  • here we are here we've got to magnets

  • on the end this disc and right here is a call love one now

  • if I make this spin mission to that we should

  • make electricity on

  • yet getting reading on a meter we are definitely

  • taking elect every time the magnet some

  • this moved past oil generated tiny

  • electric handsome copper wire make a lot of electricity

  • you need much bigger Kate and this is what Armstrong board

  • Thomson vortex turbine agran peace equipment

  • the thompson turbine needs a huge volume of fast-flowing water to drive the road

  • Lord Armstrong has available

  • is a tiny stream trickling through his estate

  • what he needed was this a lotta water

  • hud's again this on a small stream a

  • built a dam mom

  • Armstrong builds and Perth wall nearly ten meters high

  • which turns history into a deeply

  • this massive water pushing down increases the pressure at the moment

  • Armstrong channels this high pressure water down through a pipe

  • to the bottom now

  • he injected into a Thomson to her by with Tara

  • spins the world

  • this in turn road takes a shot lead to a generator

  • the produces four thousand wats electricity

  • for Armstrong this is only the first step to enlightenment

  • now he needs to get the electricity from the turbine house at the bottom it is

  • Dom

  • all the way to his picture gallery over a kilometer away

  • Armstrong connect two strands of the copper wire to the generator

  • to carry the electricity up to as much all in all

  • uses five tons of copper to power

  • a single like gold

  • but he has created a world-first house

  • let's by the power above water ok

  • on the other side of the planet in central China the Three Gorges Dam

  • takes Lord Armstrong's concept to the extreme British engineer Robin Charlwood

  • has been working on the time since 2003

  • and is still impressed by its scale

  • wherein

  • wanna 3 very large powerhouse Three Gorges Project

  • in this seven hundred meter long from here

  • you can see 40

  • large turbine generators then

  • me on this one kilometer away second

  • house then be on that one yet another powerhouse

  • to be underground at the Rock the Bogside their each one of these

  • generators cost about $50 million dollars

  • good idea at this scale this project damn damn damn

  • have one generator Three Gorges has 32

  • together they produced by million times more power than

  • them

  • to drive them the chinese have harnessed the power

  • the mighty Yangtze River in the reservoir behind the dam

  • the river now rises up to 60 stories about

  • river

  • water is channeled down gigantic concrete choose to walk the generators

  • here the torrent water hits the turbines and makes

  • spent

  • this motion is in turn transferred to the rotary general

  • this is fitted with a massive magnets which moved past copper coils in the

  • casing

  • to generate electricity

  • just wanna these machines makes as much

  • electricity as a small nuclear power plant

  • 132 generators together

  • produced enough power for $60 million Chinese

  • this project is setting a new benchmark in the international hydro-electric

  • industry

  • it's almost twice the size of the next largest project

  • it out Brazil cause is only the first a whole series that make it at

  • are under construction here in China

  • back in 1878 dead and I'm showed that even the smallest

  • dream can be harnessed to produce electricity

  • but to generate power on a larger scale engineers had to wrestle with bigger

  • returns

  • to build a dam that could produce a 128 make

  • once French engineers had to persuade the raging

  • Dordogne river to run courts

  • France in 1940

  • the outbreak of the First World War plunged the country into a deep

  • energy crisis with that cold feels occupied by the germans

  • the French are forced to import coal from abroad

  • to feed their power plants and keep the country

  • going so after the war they decide to boost the nation's power supply

  • with electricity from a hydro-electric dam but building a concrete dam in the

  • fast-flowing Dordogne river

  • presents quite a challenge and this is all a mighty river Dordogne

  • here on the beach now you call

  • just Paul concrete in the Middle River they wanted their damn

  • here but not to get one damn they had to build three

  • for civil a temperate damn goes in here

  • what's called a copper damn that stops the river flowing

  • be cut to stop it is gonna go over the top unless you do something different

  • bill

  • a diversion channel right round at and then

  • to stop it backing back up again you put in a second cofferdam

  • he annual spacing between which you can drain

  • and its there you can build your main damn

  • at the door died

  • engineers blasts two tunnels through the rock to carry the diverted river

  • they drop steel cages containing

  • rocks into the river to make that temporary coffered up

  • then they strengthen it with concrete

  • now is the river behind the dam begins to rise

  • it drains through the tunnel

  • to stop this water from backing up the engine is built a second cofferdam

  • once the water drains from the river bed between the dams

  • it leaves a perfect Dreisbach to build remains

  • was completely engineers discovered when the into the central part

  • that actually the riverbed was solid will good bills

  • straighten top

  • layer by layer giant concrete structure

  • rises 30 stories up from the river

  • the engineers then close the diversion tunnels

  • and allow the reservoir to fill up and submerge the coffer dams

  • their job done

  • finally they can open the gates to the turbines

  • and stop producing Tricity

  • when the Marais aged I'm is finished

  • it produces a 128 megawatts enough to help power train line to only all

  • and supply the city of Paris 400 kilometers away

  • with electricity

  • the Yangtze River is over 6,000 kilometers long

  • and in places several kilometers wide

  • the biggest River in China it presents enormous logistical challenges to the

  • dam engineers

  • as the Yangtze

  • rises behind the Three Gorges Dam it will flood over a hundred and fifty

  • thousand acres of land along its banks

  • so the chinese have to relocate over a million people from the land behind the

  • time

  • thousands of new houses have to be built for the displaced citizens to live it

  • then the engineers can begin damn River

  • wrist and here among some in the rocks and these

  • precast concrete blocks that were used to tree

  • the coffer dams to control a river during the construction

  • the Three Gorges Project controlling the river

  • to allow the construction of this huge project was clearly a major undertaking

  • and with the Yangtze rivers 1 largest rivers in the world

  • very fast very deep so building is confidant's and

  • to allow safe construction was a major operation the Chinese claim that this

  • was the largest most difficult diversion

  • ever undertaken for hydro-electric project I'm

  • you look at the scale of it they were absolutely right this was huge

  • you

  • the engine is begin work on a series of stone cofferdam

  • to block off part of the axe was leaving a channel open for the rest in the river

  • to flow through

  • they build the first two sections of the main down on the drive reverb

  • then they dump tons of earth into the river

  • and on top of it build another cofferdam this time

  • from concrete

  • with the river held in check behind its they can finally bill

  • the last section at the bath

  • then they must remove the cofferdam

  • so that water can flow through the turbines and the main to

  • having built such substantial cover them structures it's a major challenge how to

  • remove these things

  • so in the in the earliest stages where they were built to

  • very large rocks like this then that could be handled with

  • big X greater equipment relatively conventional

  • but in the final stage where they had a solid concrete wall to remove

  • this required some serious innovation up

  • unlike the cofferdam in my rage the Chinese version is Jim told to simply

  • leave it in place

  • so the Chinese engineers build it leaving holes for explosive charges

  • on the 6th June 2006

  • they fill them with 290 tons dynamite and hold their breath

  • up

  • what has taken months to build takes only seconds to destroy

  • as the cofferdam crumbles and unleashes the water stored behind

  • you

  • it's the final test for the Three Gorges Dam

  • and it holds

  • back in 1935 them are aged I'm proved that engineers could divert rivers to

  • build powerful

  • downs

  • but to break through the 1000 megawatt American engineers building the Hoover

  • Dam

  • had to take that building material to the limit

  • in the 1930s USA decide to tackle one of their big

  • economic problems the cities in the western United States can't grow

  • because they lack both water and

  • so to break the deadlock engineers begin work on the world's biggest dan

  • the from people who worked on

  • real adventurous these guys

  • high sky I would say on a plaque hung from a row

  • of the top of the cliff and I would go along with hydraulic hammers

  • basically smashing out cliff place so that when you pour the concrete

  • up to it would fit together well

  • they poured more concrete on this damn

  • then on any other construction projects before

  • but managing so much concrete can be a big headache for a damage

  • near when you doing really big concrete poles

  • is a very particular problem that problem is hate the first thing you have

  • to understand is that concrete

  • is made up to three basic ingredients first ball you have this stuff

  • which is cement now that's the active ingredient that's what reaction changes

  • you have water which reacts with the cement and have this stuff down here

  • which is aggregate which is basically

  • style this case at hand which gives the whole

  • mixes strange now when we put this cement in here

  • what we're gonna have is a chemical reaction hydration reaction in fact and

  • its except for Nick

  • which means that the temperature this lot should rise Solis

  • and the test and see if we write we can see it rising there

  • and it's already gone up to 15 degrees C

  • and if we wait around little while longer I'll go up some more what we've

  • seen a

  • is that we do get temperature rises not much but actually when you're in the

  • middle of a great big concrete pole

  • hate has got nowhere to go and so the inside

  • lump of concrete gets hotter and hotter and hotter and expands

  • when expands it cracked the concrete is on the outside a bit

  • and if you're doing a big concrete porn and dad cracks or a bad thing

  • up if the concrete at the Hoover Dam is poured in one go

  • the concrete on the outside world cool and harden first

  • while in the core of the dow the concrete stays hot

  • and tries to expand this could stress the concrete

  • and make crime

  • all so the engineers cast the concrete for the Hoover Dam

  • in small individual blocks as the concrete in each block

  • schools it shrinks but it doesn't crap

  • the contraction leave small gaps between the blocks which

  • engineers must filled with cement up

  • but this clever design doesn't solve all the problems

  • when who the time is enormous

  • mean there's six million tonnes concrete who the debt

  • and if we were able to concentrate all over the haiti is generated by that

  • curing concrete

  • into a single oven we could cook half a million loans have bred

  • every day three years this structure

  • if that was left on its own I think it's gonna take a hundred and twenty-five

  • years

  • for it to finish shrinking cooling down basically that's not nearly quick enough

  • a guy in charge if a local Frank Crowe they callin hurry up kroger is a man in

  • a Colorado

  • River to call my dad on

  • grow embeds over 950 kilometers

  • steel water pipes into the concrete the damage

  • well he builds a huge water chilling

  • factory

  • here he Kuils River watered down to four degrees

  • and then shoot it through the pipes into the hard concrete

  • on

  • I'm this shortens the cooling time from a hundred and twenty-five years

  • to only 22 months

  • now this works a tree all have to do

  • is finish the dan cement grout up the pipes

  • and they're out there fantastic effort actually took five thousand men only

  • twenty-one months to build the structure

  • not only that they finish two years ahead of time

  • and they finish had a budget

  • the Hoover Dam stores $35 billion cubic meters of water

  • and that the time generate more power than any other dam in the world

  • with this magnificent damn behind them the cities in the American West

  • can finally begin to thrive

  • ok the Three Gorges Dam

  • takes concrete construction to new heights look at it you can just picture

  • that fitness is a concrete base in the damn

  • the hydrant 180 meters minutes

  • two kilometers long so it's a colossal amount cock

  • Three Gorges uses

  • ten times more concrete the Hoover Dam so the engineers have to pull out all

  • the stops to keep their damn cool

  • made rescue use everything in the book be

  • cool D I its materials the sands

  • before they put into the mix they added ice they did everything they could to

  • get the temperature down as low as they could

  • for it starts to warm up for myself and here

  • because the issue some other summer weather being

  • specially hardened July holders they actually went so far as to

  • user fog spray system to blow affectively a

  • fog blankets over-the-top damn with the objective

  • blocking this on a radiation from hi down into the concrete and heading to

  • the

  • it was being generated on the inside back in 1936

  • that move a damp proof that engineers could build impossibly big concrete dams

  • as long as they can cool but as dams grew they held back

  • ever more water and with it tremendous destructive power

  • to build the grand coup leader American engineers

  • to protect from a catastrophic effects about flow

  • johnstown pennsylvania

  • 30 have made 1889

  • as the town gets it by the heaviest rainfall its history

  • the tranquility the dam reservoir is about to be shot

  • on

  • it drains for 24 hours and the water

  • reaches the top done

  • soon it has nowhere to go but over the top

  • the dam fails and 20 million tons of water

  • empties in 45

  • lemme

  • a water water 80 meters high crashes down the valley and it's John's

  • utter destruction and shoes the new over 2,200 lives are lost in the flood

  • I'll

  • it is the worst disaster the US as ever seen

  • why do dams burst when they overflow

  • engineer Ed McCann explains

  • now a particular problem is when water flows

  • over the top and weakens all with the grass the ground in front here very

  • vulnerable

  • to single time scale and we're gonna have a go modeling to see if we can see

  • what happens with toes curl

  • this is our flood coming along

  • in our river and fills up behind the dam right up at the top here now

  • and the wall soon start pushing over the top in coming down

  • and it will fall down this place and scour Wayland MA

  • in you can see the damn starting to move already as the ground in front of his

  • lost

  • the damn loses its foundation begins to rotate over

  • they won't be too long before it goes all together and back

  • which is a reasonably satisfactory dam failure

  • when it goes we get a tremendous wall

  • water come down the valley and if you happen to be down there you're probably

  • dead where you can see that time Skyrim this old dam is a huge potential problem

  • it's something that absolutely has to be fixed

  • ok

  • in 1933 American engineers start work on the ground

  • coup leader across the Columbia River in the northwest

  • America a damn that dwarfs even the Hoover Dam

  • it needs three times more concrete

  • and spans three times the distance as the engineers complete the grand cooley

  • they have to make sure that what happened in Johnstown

  • won't happen here

  • ok

  • water rushing over the damn could quickly erode the riverbed

  • and cause disaster

  • so the engineers form the box move the damn into a concrete

  • run

  • ok

  • this sense the water shooting down the spillway

  • into a tumbling cortex which dissipates an edge

  • as the water cascades of the ramp it loses much of its destructive power

  • with the ramp in place engineers can safely run the largest hydro-electric

  • dam in the US

  • a title that the grand cooley dam retains to this day

  • just ok

  • the builders have the Three Gorges Dam

  • face a similar problem

  • they too must make sure that their dad is not damaged by flood water rushing

  • through

  • basically the damn hold back

  • large volume with the water during the flood period here

  • can hold back about 22 billion cubic meters of water

  • and then its release in a controlled way through this system

  • forty-six spillway gates and these shoes you can see below me here

  • the design them a spillway like this

  • has the deal with the force of the water as

  • the drops over a hundred meters in this case here

  • then achieve shoes velocity at the bottom with the damn

  • to deflect the force of the water crashing down

  • the Chinese use technology similar to the ground

  • coolly one

  • as the water levels rise engineers open a series in

  • gates to drain the flood water from the reservoir but if the water fell straight

  • down

  • could undermine the foundations so the engine is fit the spillway

  • with concrete shoes

  • unlike the grand cooley RAM

  • which is underwater the Three Gorges shoots

  • pearl the water into the air

  • once airborne the water breaks up into small droplets

  • and loses much of its destructive energy

  • it lands over a hundred meters downstream

  • where it can't do any damage

  • so now when they open a spillway gates the Chinese

  • have nothing to worry about

  • back in nineteen forty to the grand cooley showed how dams could deal with

  • the abrasive power flood

  • but to build a dam across the mighty Genesee River

  • Russia engineers had to find a way to stop the water

  • while keeping the ship's movie

  • in the 1960s the Soviet Union wanted to upscale its industrial power

  • so they plan a series of gigantic dams

  • I'm

  • one of the first the Crocs not ask Dan will stretch a whole Colomb into

  • across the river Yannis E and generate 6,000 megawatts of power

  • but this river is also the main shipping

  • to siberia and would get blocked by to

  • to keep the ships moving

  • engineers hatch an ingenious plan they will build a steel

  • trough big enough to carry shit

  • then they will push trough and ship up to the top of the time

  • here they will spend the whole contraption round and lower it back down

  • to the river

  • on the upside

  • to move the seven thousand load they will use hydraulic pumps

  • engineer

  • Ed McCann employs a hot water bottle to demonstrate the principle behind

  • hydraulic power

  • right connected to my hot water bowl is a

  • is a pipe which goes into this garden hose

  • disconnected up to this wat care let's see what happens on lifted up by about

  • about that meter some left it up to me to

  • and the pressure in this system has gone up

  • but it's not gonna enough to lift this year so there's no movement hot wall

  • but we still squashed flat on the stand back a satellite blocks on the head

  • some lifting up it's about three meters now

  • you can see the concrete blocks moving very quickly now

  • take it

  • right to talk shit about 4 meters ago

  • but you can see there is the amazing

  • power force you can get out water under pressure

  • that will be used to lift big heavy stuff

  • the russian engineers use liquid under pressure to lift

  • shins

  • in the walls of the chamber a powerful

  • pumps which squeeze hydraulic fluid under immense pressure into a set of

  • motors mounted below

  • up these drive huge deal

  • clogs the propel the trough along guide

  • the motors generates so much traction that they left the chamber from river to

  • reservoir

  • in only 19 minutes

  • when the ship left is open the citizens have crews now

  • ask turn out in droves

  • this mechanical marvel is the crowning glory

  • the biggest diamond work

  • car China's Three Gorges Dam the engineers

  • also face a major traffic problems their damn said some one of the busiest rivers

  • in Asia

  • the Yangtze is a really important waterway

  • or navigation traffic in china the

  • alway from Shanghai the coast the chain

  • or eat it wrong it's been carrying about 18 million

  • pounds and freight per year

  • getting about a hundred and seventy ships

  • day over a damn that's more than a hundred meters high

  • is a tool order for the engineers befitting the biggest down on earth

  • the Chinese solve it by building the biggest ship block on

  • ships enter the lock at the bottom of the pan

  • gates close water floods in

  • and lifts the ship's of the next

  • ships must go through 5t is a blocks to get to the top

  • which can take up to four hours

  • this is fine for cargo ships but for the many passenger boats operating on the

  • Yangtze

  • it's just too slow to provide a more efficient transit opportunity for

  • passenger traffic they've built this shiftless system here

  • which allow boats to go through in about 36 minutes

  • unlike the ship left it cause may ask

  • the one at the Three Gorges will lift ship straight up

  • like an elevator

  • and the secretive its success life hit

  • in its concrete wall

  • ok

  • the engineers will fit a series of massive counterweights that will do most

  • lifting

  • 16 1,000 tonne concrete blocks will be connected by

  • cables to the steel trough that will carry the ship

  • and the water and floats

  • as the counterweights drawn they will placed the trough

  • upwards and left the ship to the top

  • home

  • this ship left here is 130 meters

  • hi and can handle vessels up to three thousand tonnes

  • you make it largest in the world twice the size

  • the one across

  • 10 certainly when you look at the structure now it's

  • got a ways to go terms and construction won't be finished till 2050

  • but its it's clearly huge some another very impressive achievement on the way

  • here

  • after a hundred and thirty years

  • innovation dams have produced ever more power

  • today there is hardly a former energy that is as clean as hydroelectric power

  • but as dams grow bigger so does their impact on the environment

  • in their design the Three Gorges Dam Chinese engineers have to make sure that

  • their structure doesn't completely blow

  • nature's way of feeding line

  • the Three Gorges Dam produces more power than

  • any other but that's not the main reason with bill

  • the Yangtze River is notorious for its really severe flooding

  • over the last two thousand years as being

  • about one major flood every 10 years

  • in 1931 there was a really bad one killed

  • about 235,000 people destroyed almost two million homes

  • and so that this is the main reason why the built three gorges dam is to control

  • this

  • terrible flooding problem the dam blocks the path

  • the destructive flood water

  • the water is stored in its reservoir

  • and is then released in a controlled way

  • the managing floodwater

  • can also have serious environmental side effects

  • as recent history show

  • in nineteen seventy Egyptian engineers build the as one Hyde

  • damn across the River Nile to control flooding

  • but soon farmers downstream

  • notice that their harvests are beginning to fail

  • this soil becomes so barren the farmers need millions of tons of fertilizer

  • every year to nourish their crops their land has suffered

  • because it has been deprived of floodwater which carries with it

  • the vital building blocks life

  • chemist doctor Andrew should look demonstrates

  • so we have here are clean rainwater which has been falling

  • we adding to its in good quality topsoil

  • we then some animal extra months

  • we have some snail shells

  • essentially made of calcium carbonate then we have some

  • drive leaves clock widget Asian here

  • and of course fish

  • as the

  • store proceeds as the water starts to flow rapidly

  • all these ingredients get mash top in the

  • hugely violent storm waters which occur

  • so here we have it

  • a veritable cocktail mother nature's

  • most important plant nutrients nitrogen

  • force for us counts %um magnesium

  • and potassium

  • but if floodwaters stops flowing these nutritious particles of silt will begin

  • to settle

  • this is a big problem especially in the biggest damn

  • 1

  • the flow of pressures yangtze silt is blocked by the dow

  • and trapped in the slow-moving rest

  • it rapidly sinks to the bottom

  • word built up

  • sorting problem the Yanks is a huge problem

  • total amount coming down it's about 500 million

  • tons per year which equates to about

  • one kilometer cue absent after Phil

  • big sports stadiums hundreds of times it's a huge boobs

  • if this silt remains trapped behind the day it would mean the farmers fishermen

  • and wildlife

  • would be deprived nutrients in the water the hundreds of miles downstream

  • home

  • and the tons have settled silt sentiment could build up in the reservoir and

  • threatened the damage cell

  • base sediment falling into the reservoir here with reduce the the capacity the

  • reservoir capacity in but eventually perhaps interfere with the ability to

  • run the turbine suppliers

  • came up

  • cleverly the Chinese engineers exploit the power

  • Lord flush the sediment out to the reservoir

  • and send it downstream

  • they installed sluice gates deep inside the bat

  • each gateways as much as a bus and needs a powerful hydraulic piston to lift it

  • up

  • when the operators open the games

  • floodwater rushes over the trap sediment and sweep through the dam

  • gold

  • this way the chinese authorities hope that it will be at least another 100

  • years before the buildup of sentiment

  • affect power production the time

  • good even the clever purging system cannot carry

  • all the sentiment across the damn scientific estimates on how much

  • sentiment remains behind

  • vary from as little as 30 percent to as much as 60 percent

  • the chinese authorities believe that this is a price worth paying

  • they are convinced that the benefits and the damn

  • such as clean energy flood control far outweigh

  • significant drawbacks

  • as the Three Gorges Project draws to completion

  • its scale is breathtaking

  • even with some with its turbines still to be switched on

  • it produces more power than any other time in the world

  • standing on the shoulders of historic engineering Giants

  • the Three Gorges really is ultimate

  • hydro-electric dam until someone builds

  • an even bigger

from the waters in the Yangtze River in China

字幕與單字

單字即點即查 點擊單字可以查詢單字解釋

B2 中高級

國家地理。Big,Bigger,Biggest: Dam S02E08 (National Geographic: Big,Bigger,Biggest:Dam S02E08)

  • 1434 63
    Jason 發佈於 2021 年 01 月 14 日
影片單字