Many hundreds of years ago, the moon was a mystery to people on the earth. What was that glowing ball came out at night? Why did it keep getting smaller, then larger? Why didn't it fall from the sky? Through the ages, people have tried to come up with answers.

    To the native people of Bolivia, in South American, the moon was a great chief who once lived on the earth. The Abaluyian people of Kenya, in Africa, believe the moon and the sun were brothers who fought in the sky. In other parts of the world, people believed they saw different pictures in the moon. The Haida Indians of Canada saw a woman carrying a bucket. The Chinese saw a road.

    People in the past also used the moon to mark time as a kind of calendar. In fact, in some languages, the word for moon meant “month”. A Native American nation called the Sioux made a calendar of 13 moons, or months. Each moon had a name, such as Moon of Black Cherries, Moon of Green Corn, and Moon of Severe Cold.

    Though people of the past found the moon was helpful, mysterious and interesting, they didn't know much about it. They only knew what they could see with their own eyes.

    Then almost 400 years age, an Italian scientist named Galileo made a new telescope(望远镜) that was more powerful than any telescope made before. Galileo decided to take his new implement to look at the moon. He discovered that the moon was not the smooth, shiny ball. The brighter places were mostly hills and mountains. The flat areas were lower, which is why they appeared darker.

    As more people saw the moon through telescopes, they discovered more about it. Yet, people still had much to learn about the moon.

    Soon computers and other machines will be able to remember you by looking at your eyes! The program works because everyone's eyes are different. So in the future you won't have to remember the number of your credit card when you want to use a machine or take money out of a bank. You'll just have to look at the machine and it will be able to tell who you are.

    The eye-recognition（眼睛识别）program has already been tested in shops and banks in the USA, Britain, Spain, Italy and Turkey. Soon this technology will take the place of all other ways of finding out who people are.

    Eye-recognition is a course of recognizing iris（虹膜）, which includes the following steps. First, a kind of machine needs to collect different examples of one's iris from his eyes and store them. Second, when this person goes to the bank to take out money, this machine will have iris feature extraction（采集）. Then, this machine will compare the examples kept in it with iris feature extraction. Once the examples and the feature extraction are the same, this person will be identified, and he will take out the money from the bank successfully.

    However, scientists are also working on other systems. Machines will soon be able to know you from the shape of your face or hand or even your smell! We already have machines that can tell who you are from your voice or the mark made by your finger.

    Eye-recognition is better than other kinds because your eyes don't change as you get older, and don't get dirty like hands or fingers, and even twins have different eyes. So the eye-recognition program can be up to 94% correct, depending on how good the technology is. However, some other programs may only be 51% correct now. In Britain, it was found that 91% of people who had tried it said that they liked the idea of eye-recognition.

    In the future your computer will be looking you in the eye. So smile!

    Thousands of years ago,in the south of ancient China,there lived Shennong,a man who had an ox head and human body.Seeing that local people were suffering from disease,he built ladders and houses on a high mountain to store hundreds of medical plants.To remember him,people named the place shennongjia.

    The legend(传说）makes Shennongjia in Hubei an inciting place for tourists.Traveling there is a unique experience,as you can see sceneries of the four seasons from different altitudes(海拔）.“When the bottom of the mountain is summer,the top is spring and while the foothill is autumn,the top is covered with ice,”local people say of the special climate of Shennongjia.

    Shennongjia is also home to 5,000 species of animals and plants.Many animals in danger live there,such as the golden monkey,the clouded leopard and the Asian black bear.

    One interesting and mysterious(奇妙的）thing about Shennongjia is its legend of wild men.Some people once claimed that they saw big prints or big-foot creatures.Yet so far,scientists haven't proved it is true and some say they are just bears.

    The beautiful place has recently received a new title.On July 17,2016,Shennongjia Forestry District was added to United Nations World Heritage list as a natural site.Chins now has 50 world heritage sites(遗址），second only to Italy in the world.

    Sheridan is a town in Indiana, USA. There are lots of trees near the public schools in the town. Their leaves turn sunlight into energy（能量）.

    In Sheridan, the sun not just provides energy for plants. It keeps schools running, too. The schools use solar panels（太阳能电池板） to turn sunlight into energy.

    The science behind solar energy is not new. But Sheridan Community Schools is the first school district(学区) in Indiana to be completely solar-powered. The district finished putting in solar panels for all three of its schools in 2016. Some of the panels can turn to follow the sun across the sky.

    In 2008, fewer than 1. 000 schools used solar power. By 2014, there were 3, 727 schools with solar panels in the USA. These numbers come from a report by the Solar Foundation. Roxie Brown, a program director there said that the number of schools with solar panels has continued to go up since 2014.

    Solar energy has some advantages over other energy sources(来源). Sunlight is a renewable source, which means it won't run out. Solar panels don't harm the environment. Also, sunlight is free. So by using solar power, schools can save money on energy costs.

    Brown thinks more schools should run on solar energy. "The sun is Earth s energy source," she says. "We're trying to make it the energy source for our houses cars and schools, too."

    But using solar energy isn't always easy. Solar panels can be expensive to put in. The panels also take up space. But for many schools, going solar is worth it.

    Imagine one day, the water taps (水龙头) in your house stop running. You have to buy water from shops. And still there isn't enough for everyone. Your mother has to save the family's shower water to do other things. Would you be able to stand that kind of life?

    Probably not. But that's what kids in Yemen are experiencing. Experts said Yemen is going to be the first country in the world to run out of water. According to a report, the capital, Sana, will run out of drinking water as early as 2025.

    Because of the shortage, the government often cuts the water supply(供应). Hannan, an 18-year-old from Lahej, told Times, "In a good week we'll have a water supply all week. But then the following week there will be water only for a day or two."

    Hannan said only rich people have enough water to use. They can buy water from the shops or from the water trucks. Private companies own the trucks. They travel around the city every day to sell water—at very high prices. "A lot of people can't afford it," she said.

    The average(平均) person in Yemen uses 100 to 200 cubic(立方) meters of water per year. That is far below the international water poverty(贫困) line of 1,000 cubic meters.

    The government is thinking of making use of seawater. But it will cost a lot and it may not happen soon enough to help the people of Yemen.