Many scientists say that the world is getting hotter and hotter. If they are right, the ice at the North and South Pole will melt eventually. If this happens, the sea will 1 and may cover most or all of Singapore. This will force everybody to move to a 2 country.

    We know that the sun 3 the earth. The heat from the sun hits the ground, and some of it goes back into the sky. However, factories and cars 4 a lot of carbon dioxide (二氧化碳). When the gas rises into the sky, the heat from the sun can come through them but the heat from the ground cannot. It 5 near us in the sky and makes the 6 hotter and hotter every year.

    Scientists 7 this the “greenhouse effect” because a greenhouse is a small glass building which is hot inside. It is used for     8 plants in cool countries. Many countries are 9 about the “greenhouse effect”. They are trying to stop factories and cars from sending  10 gases into the sky. Scientists are not sure when the world will get much hotter. Some people say that the “greenhouse effect" has started already and has begun to affect (影响) the world's weather.

    BEIJING—The sky is gray and air smells strange．It's another day of smog．On Saturday，heavy haze (霾) still covered north and east China．Highways were closed and1 couldn't take off on time．

    The smoggy weather 2 the country's land from north to south，including Beijing, Hebei， Shandong，and 60ther provinces．People could only see clearly 3 than 50 meters in some areas．

    Cities 4 Shanghai and Nanjing have been covered by the gray sky for the past several days．Many walkers in the street had to wear 5 ． In the Lukou airport in Nanjing more than 60 flights were canceled on Saturday 6 the haze，which also made primary and middle schools and kindergartens stop 7on Thursday and Friday in Nanjing．

    The office worker of Environmental Protection said earlier this week that there were several 8 reasons behind the widespread haze：unpleasant weather conditions making9 difficult for smog to disappear，automobile exhaust(尾气)，and coal use for winter heating．

    To fight pollution，the Chinese government now plans to clean up the air by cutting coal use，10 some factories，and removing 6 million old cars from the roads．

     “We must face up to the facts，”said Yan Naiqiang，a professor of environmental science at Shanghai Jiao Tong University．“The treatment of smog will be a long fight． From now on，if we use buses or cars less and do more tidin9，we believe a clear sky is not a faraway dream．”

    National Eye Care Day on June 6th is a good chance for us to improve our eye health. What are common eye problems we have today? How can we protect our eyes? Read on to find out the answer.

    Eyes are important in our everyday life. We use them to read books, see colors and view the wonders of the world. But sometimes, we use them too much and it hurts them.

    In the past , nearsightedness（近视）was a common eye problem among children . This is mostly because of their bad eye habits, such as watching TV too long and reading books in bed .

    However , today's technology is changing the way we live . Children spend more time working and playing in front of computers , smart phones and iPads . US children spend more than 42 hours a week in front of electronic screens（电子屏幕）, US'ABC news reported .

    This has caused a new problem for our eyes : digital（数字的）eyestrain（眼疲劳）. People with digital eyestrain may get headaches , dry and red eyes , eye pain , watering and other eye problems .But don't worry . The following tips can help you protect your eyes . Try them out .

Screen advice :

⒈ When you are watching electronic screens , keep them at least 30 cm from your eyes . Try not to use your smart phone in direct sunlight .

⒉ Blink（眨眼）more often when you are looking at the screen . This can help to stop dry eyes .

⒊ Remember to take a 20-20-20 break : every 20 minutes , take a 20second break and look at something 20 feet ( about 6 meters ) away .

⒋ Spend less time in front of screens . One to two hours a day is OK for your eyes .

    Hundreds of years ago, life was much harder than it is today. People didn't have modern machines.

    There was no modern medicine 1.

    Life today2new problems. One of the biggest is pollution. Water pollution has made our rivers and lakes dirty. It kills our fish and affects (影响) our drinking water. Noise pollution makes us 3 louder and get angry much easier. Air pollution is the most serious kind of pollution. It affects 4 living thing in the world.

    Cars, planes and factories all pollute our air every day. Sometimes the pollution is5thick that it is like a quilt (被状物)over a city. This kind of quilt is called smog(烟雾).

    You either have it, or you don't—a sense of direction, that is. But why is it that some people could find their way across the Sahara without a map, while others can lose themselves in the next street?

    Scientists say we're all born with a sense of direction, 1it is not properly understood how it works. One theory is that people with a good sense of direction have simply worked harder at developing it. Research being carried out at Liverpool University supports this idea and suggests that if we don't use it, we lose it.

    "Children as young as seven have the ability to find their way around." Says Jim Martland, Research Director of the project. "However, if they are not allowed out alone or are taken everywhere by car, they2develop the skills."

    Jim Martland also emphasizes that young people should be taught certain skills to 3their sense of direction. He makes the following suggestions：

    If you are using a4, turn it so it relates to the way you are facing.

    If you leave your-bike in a5place, put it near something like a big stone or a tree. Note landmarks on the route as you go away from your bike. When you return, go back along the same route.

    Simplify the way of finding your direction by using lines such as streets in a town, streams, or walls in the countryside to guide you. Count your steps so that you know6you have gone and note any landmarks such as tower blocks or hills which can help to find out where you are.

    Now you need never get lost again!