In nature，you may see many insects and animals of different colors．Have you ever wondered why?

Locusts(蝗虫)are super delicious food for birds，but it is not always an easy job for birds to catch them．It is neither because locusts are good jumpers or runners nor because they are smarter than their enemies．The reason is that the colors of locusts change with the colors of crops(农作物)．When crops are young，locusts look green．But when autumn comes，locusts change to the yellow and brown color as crops do．

    Brown bears，tigers and other animals move quietly through forests．They can't be seen easily by their enemies．This is because they have colors similar to the trees．For the same reason．polar bears that live on a land of snow and ice are white．Butterflies and bees living among the flowers are colorful like flowers．Soil insects are mostly dark—colored and they live under the soil in a dark and wet environment．However，insects with colors different from plants can easily be found and eaten by others．So in order to survive ， they have to hide themselves in the daytime and appear only at night．

    Have you ever noticed some even stranger acts? The ink fish in the sea can send out some very black ink when it faces danger．As the ink spreads over．its enemies will not find themselves suddenly in a dark world．At the same time the ink fish immediately swims away．That is how it keeps itself save though it is not strong at all．

    From a plane we can see the fields, cities, mountains or seas below. If we go into space, we see more and more of the Earth. People and man-made satellites have been sent out into space to observe the Earth carefully and people have learnt mire about the Earth in the last few years.

    The sea looks very beautiful when the Sun is shining on it. But it can be very terrible when there is a strong wind.

    The sea is very huge. It nearly covers three quarters of the Earth. The sea is also very deep in some places. There is one place where the sea is about 11 kilometers in depth. The highest mountain is the world is about 9 kilometers high. If that mountain was put into the sea at that place, there would be still 2 kilometers of water above it!

    In most parts of the sea, there are many kinds of fishes and plants. Some live near the top of the sea. Others live deep down. There are also a lot of small living things, and quantities of fishes live by eating them.

    The sea can be very cold. When people go down, the sea becomes colder and colder. Only some men could go down into the deep sea at first. But in 1970, five women scientists lived in the deep sea for fourteen days.

    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.

People never get a second chance to make a first impression（第一印象）. {#blank#}1{#/blank#} Here are some skills to make you look wiser.

Plan ahead.Whether you're talking in a private room or at a wide hall，the most important thing you can do is to make yourself heard clearly.{#blank#}2{#/blank#}If you're interviewing for a job，take advantage of Google to know the information about the company.If you're going on a date，plan some talking points{#blank#}3{#/blank#}And that will also improve your confidence.

{#blank#}4{#/blank#}Good eye contact means the other person is reacting to what you are doing or saying.If someone looks at you while you're talking，you probably think the person is smart.Researchers at Brandeis University found that people who kept eye contact scored higher on IQ tests than those who avoided eye contact.

Take a proper posture（姿势）.{#blank#}5{#/blank#}To show self﹣confidence in a meeting，you can sit up straight and leave your arms widely spread at your sides.Holding the posture for just two minutes can lower stress and increase feelings of power.

A、Make eye contact with others.
B、Feeling prepared will make you relaxed.
C、Openness can carry the meaning of confidence.
D、The key to overcoming nervousness is to make full preparations.
E、Usually，we get the first impression about others based on how they behave themselves.

Greenland is the largest island in the world. It's in the northeast of North America. Near Greenland is another island. It's small. Its name is Iceland. Do you think that Greenland is green and warm? Do you think that Iceland is white with ice? If you do, you're wrong. That is because most of Greenland is covered with lots of ice. The ice is higher than the world's tallest building. There are more people in your hometown than those in Greenland. What about Iceland? Iceland has ice, but not so much ice as Greenland. Iceland has lots of hot spring (温泉). They give out hot water and steam. The climate (气候) is less cold than that in Greenland. And there are a lot more people living in Iceland.