Save the world's trees

"When it comes to the Earth，there is no time to waste．"says the Earth Day Network．And that is right．Protecting our environment is very important，and World Earth Day was created in 1970to ask more people to protect our environment．On April 22，people around the world celebrate Earth Day．

Every year there is a special topic，and this year it is "Trees for the Earth"，so Earth Day this year will be all about planting trees．They are planning to plant 7.8billion trees within the next five years

That's a big goal，and you might wonder why trees are so important．Because they can take in carbon dioxide （CO₂） and protect the air quality（质量）．CO₂is a chemical in our atmosphere，but humans make too much of it．Each person makes about 2.3tons a year，which is bad for the environment．

Well guess what! Planting new trees is important because people cut down a huge number of trees．Last year，there were 3trillion trees in the world，about 139billion in China．But according to China Daily，the world's total number has been almost cut in half since human civilization（文明） began．That's because 15billion trees are cut down every year．

So we need to plant more to make up for（弥补）the ones we lost．One tree can take in 21.8kilograms of CO₂ per year．And   it's still one of the cheapest and best ways to get rid of CO₂．

But don't forget that we can also help the environment by cutting down on how much energy（能源） or water we use every day．Every little thing helps．

根据短文内容，回答问题（66﹣69），英译汉（70）．

66．When do people around the world celebrate World Earth Day？

　　

67．What is the topic of Earth Day？

　　

68．Why are trees so important to the earth？

　　

69．How much CO₂ can two trees take in each year？

　　

70．Put the sentence "It's still one of the cheapest and best ways to get rid of CO₂．"into Chinese．

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