Bats are the only “flying animals” in the world. They can't see very well. We often hear “as blind as a bat”. Yet they have no trouble flying on the darkest nights and finding their ways round. How can bats fly and see at night? They fly by radar(雷达).

The bat's radar system(系统) works the same way as the radar in ships and planes. As a bat flies through the air, it makes a sound. If the sound hits things, it will come back and the bat's ears will receive the message. In this way the bat is able to know where the things are. Bats go out for food at night. In the daytime they hang in some dark places. Some people think bats are bad animals. In fact they are useful animals.

    The best-known (最熟知的) vegetable in the world is the potato. It grows in many places and does not need rich soil(土壤) like many other crops. But until four hundred years ago, the Europeans(欧洲人) began to know the potato. But today it's one of the main foods in Europe(欧洲). About half of the world's potatoes are grown in Europe.

    In France the potato was not grown for a long time .Here is story about Louis. In 1778 he saw some potato flowers for the first time .He liked them so much that he picked one and put it in his buttonhole. He was interested in the flowers not the potatoes themselves.

    Now, it seems that artficial intelligence （人工智能）is becoming more and more popular in our life, and it has greatly influenced the ways we live, work and play. Can you imagine that you can play table tennis with a robot one day?

    Recently, a scientist has invented a special robot that can be a table tennis coach. That means people can practice table tennis not only with humans but also with a robot.

    Named Forpheus, the smart table tennis robot is quite special. It can study the movements of human players and the speeds of the ball. In this way, it can exactly judge (判断) the player' skill levels (水平). Then it uses the information to change the ways to play. If the player are just beginners, Forpheus will play in a slow and easy way, but if the players are better ones, the robot will play in a faster and more difficult way. What's more, while playing, it encourages players to try their beat with words like "Good job!", "Come on!" and so on. At the same time, it gives some good advice to improve their skills. So it is both a good partner and a clever coach.

    Science and technology is developing quickly these days and it's hard to imagine what will happen in the future. "In the next 20 years, it will be possible that one robot teaches another to play table tennis or even invents another one!" Takuoya, the inventor of the robot, said.

    What can 3-D printers*make? They can make lots of things, such as toys and car parts. But what about a house? In the Netherland 3-D printed houses will soon come into life, according to The Guardian

The Netherlands is the first country to have this technology*.

    Scientists plan to build five houses with 3-D printers. The first house will be finished by the end of 2019. It will be a house with three bedrooms. For the first house, only the walls will be 3-D printed. A 3-D printer will print it with a special cement. The printer will print it layer upon layer to build the walls. After that, workers will make the wall stronger.

    By the time they start working on the fifth house, the scientists hope that most parts of the house will be made with 3-D printing. Even the windows can be made with a 3-D printer.

    The 3-D printed houses have many advantages. For example, they use less cement than traditional houses. It can help save a lot of money. Also, 3-D printing can make buildings in almost any shape*. Traditionally-built homes usually come in just a few shapes