People usually check whether their keys, purses and phones are with them before going out, but many people in China now have one more important thing to take--a mask(口罩). They hope it can protect them 1 terrible air.

    Many cities in China saw a lot of foggy days in April. In Beijing, there were eight days in April full of smog. It is dirty air 2 looks like a mixture of fog and smoke. The smoke is mainly from cars and factories in cities. Poor air is bad for people's health, 3 for children and old people. They fell ill easily and the 4 were full of people. They had problems with their noses and lungs.

    So it's necessary 5 people from doing so many bad things to the environment. For example, people should use cars less and   6 burn lots of coal and gas. Government needs to take measures to make factories stop pouring 7 waste air into the sky.

    Three students from No. 4 High School in Beijing 8 a report to advise how to protect the environment. They suggested  9people should plant more trees and act off fewer fireworks for celebration. We hope more people will join us in 10 a difference. In this way, the blue sky will certainly return for good.

    In the universe, as we know, there is the Sun, the moon, the Earth and a good many stars. Through our geography lessons, we know the Earth goes around the Sun, and the moon goes around the Earth. We have day and night because the Earth keeps turning all the time. When our part of the Earth turns to the Sun, it is day. When our part of the Earth turns away from the Sun, it is night.

    Just because the moon is closer to the Earth than the Sun, it looks much bigger than the Sun. Big things will look smaller when they are farther, and small things also look bigger when they are nearer.

    The Sun is bright enough to give out very strong light. The moon can't give any light at all, but it looks quite bright, too. Why？In fact, the light from the moon comes from the Sun. The moon looks much bigger and brighter than the stars. But actually (事实上) the stars are much bigger and brighter than the moon. They look smaller than the moon also because they are farther away from the Earth.

    There are still many other planets in the universe. But of all these planets, only on Earth there are living things and people can only live on Earth, too. But at 9∶00 am on October 15th 2003,Chinese astronaut Yang Liwei was set up to space. He stayed there for 21 hours. It was the first time for Chinese to get into space.

    The name of our galaxy(星系), the Milky Way, comes from its appearance. It's a milky white band of glowing light that spreads across the night sky. If you look up at the evening sky, there's a good chance you will not be able to see what your grandmother saw when she was a little girl. A new study says that nearly 80 percent of people in North America can't see the Milky Way because of light pollution.

    The most light-polluted country in the world is Singapore where researchers found that people living in the country never have the chance to experience true darkness. Other countries with large percentages of people living under such skies include Qatar, Kuwait and the United Arab Emirates.

    Too much light has a direct influence on human physiology and behavior. It can also destroy our sleep cycle. What's more, it also influences wildlife. For example, baby turtles may not swim into the ocean because of street lights near shorelines.

    In the U.S., some communities have been taking action on light pollution but in developing countries, people still want to make bigger, brighter light, like LED lights. They can save energy, but on the other hand, they will increase light pollution rapidly in fact.

    There are still people that can remember when they used to be able to see the Milky Way, when they would walk outside at night, but those are becoming fewer and fewer.

    Nighttime natural scenery needs protection just like daytime scenery. Don't let the light pollution steal the chance to experience the wonder of a natural night sky from us.

    Have you noticed the waste bins(垃圾桶) in different colors on the street? Do you often put all the waste in the same bin? It's reported by Changchun Daily that people must do waste sorting(分类)in most places in Changchun at the end of 2019. Waste sorting is a wonderful way to make good use of energy and protect the environment. But do you know how to sort the waste?

    Usually, people should sort their waste into four groups: wet, recyclable, harmful and dry. Different kinds of waste should go into different bins. Wet waste means the things you don't want but pigs can eat, mostly coming from your kitchen. Things that can be used again, such as paper, metal and glass, are recyclable waste. Harmful waste might be dangerous or cause serious pollution, like medicine and batteries(电池). And any waste that's not wet, recyclable or harmful will go into the dry waste bin.

    Different countries are trying different methods to sort the waste. A university in England has invented a smart bin. When people drop their waste into the bin. It can tell what kind of waste it it and sort it correctly. The bin can also compress the waste to make it smaller in size and take up less space. In South Korea, people have to separate their food waste from other kinds of waste and pay for it. The more food waste they throw away, the more they pay. Japan has the strictest rules for waste sorting in the world. For example, plastic bottles and their caps should go into different bins.

    What is the hardest sport in the world? Some people say it's boxing (拳击), because boxing is dangerous and boxers have to be strong and fast. Other people say the hardest sport is soccer.

    However, most people say the hardest sport is the triathlon (三项全能运动). A triathlon is a race that includes three sports. First, racers swim. After that they ride bicycles and finally they run. In the most common triathlon, racers swim 1.5kilometres, bike 40 kilometres, and run 10 kilometres. The winner is the person who finishes the race first.

    There is another kind of triathlon too. It is called the "Ironman Triathlon (铁人三项)". This triathlon is much longer. People who finish this triathlon are called "ironmen" or "ironwomen". This is because these people are so strong that their bodies are just like iron (铁).

    In the past, there were other races including three sports. However, they didn't use the word "triathlon". That word was first used to describe a race in California in 1974.

    Triathlon racers have to train very hard for their races. Many of them swim and run. A lot of people also do things like yoga (瑜伽). They have many different ways to prepare, but they all have the same goal. They want to be in perfect shape.

    To be an ironman or an ironwoman, you have to be strong and smart. You should know how to save energy during the race.