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    For many years, scientists have said that the earth is getting warmer. Now they have found something new—hot cities! In the southern US, they have found that cities become very hot in summer. For example, the city of Atlanta in Georgia has roof(屋顶) temperature of up to 50^oC while it is 27℃ in the streets! At night, the outside of buildings stays so hot that the heat of the city causes storms over the city!

    China also has the same kind of problems. Every year more farmland is used for factories or offices. More housing is needed, too. As people become richer, they buy more cars. New roads are needed and new car parks are built in the city centers. This all makes cities hotter.

    It isn't easy to change the situation. City planners say that we should plant more trees in the middle of cities. Every new street should have trees on both sides, they say. Trees make the temperature lower, so we should have more trees in our parks and squares. We should also paint our roofs white. If we do this, they do not become so hot. Every roof in a hot and sunny country should have solar(太阳的) roof panels. The electricity from these can be used to run the air conditioners (空调)in the buildings.

    People continue to cut down forests around the cities. This makes the problem worse. Cities are growing faster and faster. By the year 2025, four fifths(五分之四) of the population will be living in cities. If we go on like this, there will not be enough farmland to feed everyone in the world.

    Since ancient times, human beings have looked up at the night sky. Comets (彗星) and meteors (流星) flying through the blackness were seen as signs from the gods. They were used to tell the future of human lives.

    In 2013, a meteorite shower hit an area in Russia. It injured around 1,200 people. In ancient times, this would have been a strange and terrible experience. Today, thought, science offers simple explanations for the occurrence (事件).

    Meteorites are small pieces of debris (碎片) that float around in space. Sometimes, they come near a planet, such as Earth. When they enter our atmosphere, they often heat up and become very bright. This is why they are sometimes called “fireballs”. They are usually made of metals, such as iron (铁), and other minerals (矿物). The Russian meteorites were stony, with iron making up 10 percent of them.

    Meteorite showers, such as that in Russia, happen when a large meteor enters the Earth's atmosphere and, due to heat, breaks up into small parts. Most of these are very small — smaller than a grain of sand — and so don't even make it to the ground. But others can cause a lot of damage.

    The meteor in Russia weighed 10 tons when it entered our atmosphere, and broke up about 20-30 miles (30-50 km) above ground. The sky was filled with bright lights and loud noises. Many windows were broken. The damage cost Russia around 206 million yuan.

    A series of Chinese landscapes (风景) created by an AI (人工智能) robot, named Gemini, is shown in London.

    It was believed to be the first AI-made ink work. Ink Now Chairman Calvin Hui sees it as the start of the tech ink times.

    It took Victor Wong, the Hong Kong artist, around three years to build and program Gemini. He has been interested in traditional art since he was young. "Few younger people nowadays care about ink, so I decided to bring technology and ink art together." says the artist, "I want to tell them that ink painting is not that hard to do."

    Each landscape painting can take around 60 hours to finish. First, the robot artist creates his own landscape in his AI mind. Then he's traveling inside his mind and picking up an angle (角度) because it's 3D. After that he uses an arm that puts the brush into ink and water before sweeping across Xuan paper to create Chinese Shuimo artwork.

    However, in some people's opinion, whether robots can create ink art like human artists is not sure because the ink lines were too, straight while works created by human hands are better. "I'm open to all comments," he said, "I'm keeping an open mind as to whether machine-made art can be seen as art. But I hope it will bring an imagination to artists on how to mix technology while painting or creating.

Dear sir,

    I am doing a project(课题) at school about animals in danger. I think the situation all over the world is really terrible.

    Firstly, I feel so sorry for the giant panda. Pandas mainly live on bamboo. A panda can eat about half its body's weight(重量) of bamboo in 24 hours！That's a lot of bamboo. I think we should try to do more to stop cutting down their forests. We would be so sad if they disappear.

    Secondly, what we should try to protect more is the Chinese alligators(短吻鳄) . They live in some parts of eastern China. They live in freshwater rivers and lakes but the water in some places isn't clean enough for them to live in. It's really dirty in fact. The government should stop factories from polluting the lakes and rivers.

    If we protect these beautiful animals in China, more people may come to China to visit our beautiful country, especially to see the quieter areas in the country. Now most visitors just see the cities.

    I hope you will encourage(鼓励) more people to think about such an important subject.

Yours,

Huang Jing

    On April 2, we said goodbye to Tiangong I, China's first space lab. According to the China Manned Space Agency (中国载人航天), Tiangong I re-entered the Earth's atmosphere (大气层) and some of its debris (碎片) fell into the South Pacific Ocean.

    There are many spacecraft (宇宙飞船) that are still in orbit

     (轨道) above the Earth. After finishing their trips, they will all re-enter the Earth's atmosphere like Tiangong I.

    There are two types of re-entries: controlled re-entry and uncontrolled re-entry.

    Some satellites and manned spacecraft come back to the Earth in a controlled re-entry. Experts calculate (计算) the path of the falling spacecraft and its speed. Thy can guide the spacecraft to fall in a chosen area.

    Some spacecraft may have problems while in space after a certain amount of time. These spacecraft come back in an uncontrolled re-entry. It is hard to tell when and where these spacecraft will fall until the last few hours. The US space station Skylab came back partially uncontrolled in 1979. Parts of the station fell in western Australia, but no one was hurt.

    During re-entry, most of the spacecraft will burn up while passing through the Earth's atmosphere. Only a small amount of the debris will reach the ground. The debris typically ends up falling into the ocean, China Daily reported.