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3 . Off the coast of Formentera, an island, lives seagrass that stretches 15 kilometres. The seagrass, covering several hectares, is made up of a single organism. The grasses are also long-lived, for tens or hundreds of thousands of years. Along with two other kinds of coastal ecosystems—mangrove swamps（红树沼泽）and tidal marshes, seagrass meadows are particularly good at taking carbon dioxide from the air.

This role was highlighted in a report, which was published on March 2nd by UNESCO, on blue carbon—the carbon taken in by Earth's oceanic and coastal ecosystems. In total around 33 billion tons of carbon dioxide, about three-quarters of the world's emissions（排放）in 2019, are locked away in the planet's blue carbon sinks（碳汇）. Research by Carlos Duarte, the report's author and a marine ecologist, has shown that one hectare of seagrass can suck as much carbon dioxide each year as 15 hectares of rainforest.

One reason that blue—carbon ecosystems make such effective sinks is that underwater forests are thicker than the land-based woods. They can also trap floating pieces and organic matter, which settles on the sea floor and can double the amount of carbon stored away. They have another advantage, too. Climate change is leading to more wildfires around the world. As forests burn, their carbon stocks are released back into the atmosphere. Unlike forests on land, blue-carbon ecosystems do not burn.

Blue-carbon ecosystems may not be fired, but they remain affected to other sorts of disasters. In May 2020 hurricane Amphan destroyed 1,200 square kilometres of mangrove forest. A marine（海洋的）heatwave in Australian waters in 2010 and 2011 damaged around one third of the world's largest seagrass meadow in Shark Bay. “Mangrove forests can weaken or control waves and provide natural barriers to storm surges. Protecting and expanding them, then, appears to be a must,” said a marine biologist.

5 . Though leaders from the International Olympic Committee(IOC)have announced a first-of-its-kind postponement of the Tokyo Summer Olympics because of the corona virus epidemic,people all over the world are still concerned about its preparations.Officials from the Tokyo Olympic Committee say they are sparing no effort and announce the Tokyo Summer Olympics in 2021 is going green.The 5,000 medals Japan has made are more special than most.

One novel focus of the Tokyo Olympics is to be"sustainable”－to avoid using too many natural resources,so that the games are easy on the environment.As part of this goal,the organizers decided to make all of the Olympic medals out of metal recycled from old electronics.

Almost all electronics are made with small amounts of"precious metals",like gold and silver.But collecting enough of these metals to make 5,000 medals was a huge challenge.That's because the amount of metal in each device is tiny.It would take about 20,000 cell phones to get just l kilogram of gold.

Beginning in April 2017,the organizers placed collection boxes around the country,and asked people to turn in their old electronic devices.Soon people began to respond to the initiative(倡导），turning in smart phones,digital cameras,handheld games,and laptops.At first,collection went slowly,but soon more and more   areas began to take part.By the end,1,621 local governments had helped out with the collection process.

Then came the job of breaking those devices down into smaller pieces.After eing taken apart and sorted, the small electronics were smelted(熔炼）to get all the gold,silver,and bronze elements.This is a tricky job, which calls for careful attention and good skill.It's also dangerous,because some of the metals and other things aren't safe for people to touch or breathe.

By the end of March,2019,the organizers had hit their targets of getting enough metal for the medals. They had collected around 32 kilograms of gold,4,100 kilograms of silver and 2,200 kilograms of bronze.And now all the 5,000 medals are available for the would-be winners.

6 . Last week the electricity in my flat went out. I had just got home from work and was happily making my tea, when all of a sudden I was surrounded by complete darkness. I tried to fix it but failed. I had to wait for an electrician to come in the morning.     1    

I sat down to eat my half - cooked dinner. And then I wasn’t really sure what to do. My typical evening is spent watching the TV and looking through social media.    2     So for me it was an early night. And I couldn’t help but think, do we rely too much on electricity? That night, losing our electricity felt like losing a basic necessity. As basic as running water.    3     I use electricity all the lime, even when it’s not really necessary.

    4    . It contributes to global warming. It is harming our environment and we need to do what we can to stop it. Not only that, but if we continue to use the same large amount of energy we will soon run out.

So, shouldn’t we start preparing for it now? Cutting back on our use of electricity would make losing it easier, and also save energy resources so that they could last for longer.    5     And if everyone does the same, we can make a big difference.