We have been used to wearing masks(口罩) in public since February. About 300 million masks are used and then thrown away every day in China. Where do these masks go? You might think they just go in a rubbish bin. But that's just the first stop on the masks' journey.

After the masks are thrown into the bins, rubbish trucks empty the bins and take the rubbish to landfills(垃圾场). Next, the masks will be taken to rubbish incinerators(焚化炉) and burned. Burning masks might not seem to be very good for the environment. Won't it cause pollution?

The answer is "no", according to China Daily. The main material of most masks is polypropylene(聚丙烯).It's non-toxic(无毒的). After burning，it changes into water and Co₂.

In fact, burning the masks can bring some benefits(益处). The process of burning the rubbish can produce electricity. Burning one ton of rubbish can produce more than 400 kilowatt hours(度) of electricity. Some people make a prediction that there will be 162, 000 tons of used masks in China this year. Burning all of them can produce more than 64 million kilowatt hours of electricity. This is enough to make an electric car drive about 370 million km, which is 9,250 times as long as the earth's equator.

At last, the slag(残渣) from burning masks can be recycled to make bricks(砖块)or fill the roads.

Not only Kate's brother English, but also he likes maths.

Once there were many thousands of Gourma Desert (荒漠) elephants in Mali, a country in west Africa. Now, there are fewer than four hundred.

Why did the number of the elephants drop so quickly? On the one hand, the elephants' main lake, their only water source(来源), dried up. On the other hand, the land which the elephants lived on was overused by humans.

To protect the elephants' living environment, the Mali Elephant Project (MEP) was started in 2007. MEP met with local people and helped them make rules of using land and water. As a result, the situation became better and there was more food, forest and grassland.

However, from 2012 to 2016, poaching(偷猎) and illegal trade in the elephants increased rapidly. Eighty-three elephants were lost in 2015 alone, and another fifty-one elephants were killed in 2016."If this situation goes on, all the Gourma elephants will be killed by. 2020," said a member of MEP.

Luckily, the voice of MEP was heard. More organizations (组织) have joined together to educate the local people that trading elephants is against the law. Elephant poaching has dropped to a very low level. The local people have learned to live peacefully with the elephants, one of the wildlife treasures in the world.

Want to save the earth? Plant a tree!

What's causing global (全球的)warming? Is it man-made? Or are temperatures simply changing naturally? Whatever the case, we can at least try to slow things down, But how?

The Wilderness Project has an idea. . If the earth has more trees, greenhouse gases will be reduced, and this will help stop global warming.  and improve air quality (质量). . In Belgium, the Organization for Forests works with farmers to help them plant more trees. In Spain, the Canopy Project plants one tree for every Spaniard (西班牙人) in order to improve the environment. In Germany, a teenager named Felix Finkbeiner has been leading a global movement to plant more trees. .

Now, lots of people all over the world have already been planting more trees. In fact, if everyone plants one tree, just one, it will do great good to our environment.

So what can you do to help? , although you need to get advice on how to look after it. Or you can join a tree planting project such as the ones mentioned above to help save the earth.

So, go on, plant a tree... and save the earth!

water pollution, factories shouldn't pour waste water into those rivers directly.