There is little rain in desert. Because deserts are so dry, they have no "quilt" to help stop the soil from going away. As a result, they may get very hot during the day with the sun shining, but don't hold the heat overnight. Many deserts can quickly get cold once the sun goes down. Some deserts can reach temperatures of over 100 degrees F during the day and then drop below freezing (32 degrees F) during the night.

The largest hot and dry desert in the world is the Sahara Desert in Northern Africa. The Sahara is a sandy desert with great sand hills. It covers over 3 million square miles of Africa. Other large deserts include the Arabian Desert in the Middle East, the Gobi Desert in Northern China and Mongolia, and Kalahari Desert in Africa.

Animals that live in the desert are also used to needing little water. Many get all the water they need from the food they eat. Other animals keep water that they can use later. The camel stores up fat in its hump while other animals keep something they need in their tails.

Only certain types of plants can live in the terrible environment of the desert. You won't see a lot of tall trees in the desert. Most plants have a way to keep water in their leaves, or trunks so they can live a long time without water.

Now deserts cover around 20% of the world's land, but they are growing. This is called desertification and is caused by different reasons including human activities. The Sahara Desert is growing larger and larger each year. What should we do with it ?

    Baboons(狒狒) live in Africa. They are like monkeys. Most people think daddy baboons don't know their babies. But scientists (科学家) find that daddy baboons know how to help their babies. The daddy baboons are smart.

    Joan Silk is a scientist. She studies the baboons for 3 years. She says the daddy baboons are happy to see their babies. They have big teeth to help the babies to eat hard things. Mother baboons are small. And they live in a place. When a mother baboon gives birth(分娩), she often has only one baby. Baby baboons have fur. They are very cute.

    During the day they eat things. At night, they sleep in the trees. Most children like baboons because they look like the man.

    Do stars only appear at night? The answer is no .Venus （金星） is the one and only star that can be seen in the daytime. It shone at its brightest in the night sky on February 17^th, 2017.

    Venus is the second planet from the sun in our solar system. It is the second brightest natural object, behind Earth's moon, in the night sky. Why is it so bright?

    First of all, Venus is the closest planet to Earth. It is also covered by highly reflective （反射的）clouds, which can reflect about 70 percent of the sunlight striking（照射） it, almost twice as much as Earth does.

    Some called 2017 the year of Venus, because the planet is at its brightest when it goes further away from the sun, and nearer to Earth. The brightest moment happened once in February, and happened again, during daylight, on April 30^th.

    If Venus is so bright and close to us, isn't it a better choice for human exploration than Mars? It is closer to Earth than Mars and it's closer to Earth in size. The closer distance to the sun means solar power would be easier to generate （产生） as well.

    However, with a temperature of about 465℃on the surface, Venus is the hottest planet in our solar system!

    But scientists never give up. Recently, a team of NASA and Russian scientists created new computer equipment that can stand the temperature of 480℃. It can work under Venus-like conditions for almost 22 days.

    The next step, according to the scientists, is to send a probe（探测器）to Venus by 2025.

    If there is no rain, there will be no water to drink. We can only live for about three days without water. If there is no rain, we'll have no water to brush our teeth. We will have no water to take a shower. We will have no water to wash dishes or our clothes.

    Plants and animals need water to grow. If there is no rain, they will die. We will not have any rice, any vegetables or any meat. If there is no rain, we will have nothing to eat. We can only live for about one or two weeks without food.

    If there is no rain, there will be no water in the streams or rivers. Fish will have nowhere to live. They will die. We will have nowhere to swim.

    If there is no rain, the cooks in the restaurants will have no water to cook food.

    If there is no rain, firemen will have no water to put out fires.