"When it comes to the earth, there's no time to waste," the Earth Day Network says.And that is true.1. ______(protect) our environment is very important.World Earth Day was created in 1970 to raise people's 2.e______ awareness.3. ______ April 22, people around the world celebrate World Earth Day.
　　Every year there is a special theme.The theme was "Trees for the Earth" in 2016.Their goal is to 4. ______ 7.8 billion trees by 2020.
　　That's a big goal, and you might wonder 5. ______ trees are so important. Well for one, they can help stop climate change.Carbon dioxide (二氧化碳) is a chemical in our atmosphere, but humans make too much of it. Each person makes about 2.3 tons a year, which is 6.b______ for the environment.
　　Well guess what! Trees take in carbon dioxide and improve air quality.Planting new trees is important because people cut down countless 7.t______.
　　According to Time, the total number of trees in the world has been almost cut in half since human civilization (文明) 8. ______ (begin).So we need to plant more to replenish (补充) the ones we've lost.One tree can take in 48 pounds (21.8kg) of carbon dioxide per year.And it's still one of the 9. ______ (cheap) and best ways to get rid of carbon dioxide.
　　But don't forget that you can also help the environment by cutting down on how much energy or 10.w______ you use every day. Every little bit helps!