Language students often think they have memory problems. They worry because they can't remember words. In fact, the problem usually isn't with their memory. The problem is with how they study.

    To remember words better, you need to understand how memory works. There are two kinds of memories: short-term and long-term. When you see, hear, or read something, it goes first into short-term memory. But short-term memory lasts for only a few seconds. You will only remember something longer if it goes into long-term memory. Your long-term memory is like a very big library with many, many books. And like a library, it's organized (有条理的). When you put away a book – or memory – you can't just leave it anywhere. You have to choose a place where you can find it again.

    How can you do this with vocabulary? The answer is to work with the word and think about the word in new ways. You can do this by writing new sentences that include it. Even better, you can invent a little story about the word, with people or places that you know. Another way is to make a picture in your mind with the word. For example, if the word is height, you can think of the tallest person you know and try to guess his or her height. All of these activities are good ways to think about words. They make the meaning of words stronger in your long-term memory. And they give a way to find a word when you need it.

阅读理解

    Sixty years ago，human beings first reached the top of Mount Qomolangma， known as Mount Everest in the West. But the increase in climbers is turning the world's highest mountain into the “world's highest junkyard(垃圾场)”.

    Every year， more than 700 climbers spend nearly two months on Mount Qomolangma. They have left human waste and all kinds of rubbish， including oxygen bottles， broken tents， and plastic bags， according to Ang Tshering Sherpa， chief of the Nepal Mountaineering Association.

    “The waste has become a health danger to people in the area since they depend on water from rivers fed by the melting glaciers(融化的冰川)，” Sherpa said.

    More and more people have realized the danger that Mount Qomolangma is facing and they are now taking active actions. To deal with the problem， Nepal has supported a special team of explorers and volunteers to clean the mountain since 2008. So far they have brought down 15，000kg of rubbish. Nepal also started to ask each climber to bring down 8 kg of rubbish in 2014.

    On the Chinese side of the mountain， Tibet(西藏) will collect a cleaning fee of $100-200 (620-1240 yuan) per climber starting from this year. A program named “Mount Qomolangma Action at the Third Pole of the Earth” also started in 2004 to clear up the mountain.

    Hopefully， human beings will finally solve the problem， just as they found the way up the mountain successfully.

    Can plants eat people? Maybe not, but there are many plants that eat meat. Some of them are big and they can eat small animals. One famous meat-eating plant is the Venus flytrap(捕蝇草).

    The Venus flytrap is a very strange plant. It grows in dry parts of the United States. Its leaves are like the pages of a book. They can open and close very quickly. The fly (苍蝇) cannot get out. In about half an hour, the leaf presses (压) the fly until it is dead. Then, the plant covers(覆盖) the fly. Slowly, the plant eats the fly.

    Why do plants do it? Most plants get what they need from the sun, the air, and the ground (地面). In some places, the ground is very poor. It doesn't have all these important things, especially nitrogen(氮.). Animal meat has a lot of nitrogen, so many plants eat meat to get what they need.

    Let's hope that some of the bigger plants don't get the same idea!

    In our daily life, robots are often found to do work that is too dangerous, boring, difficult, or dirty. And we often see kids play with toy robots.

    But what exactly is a robot? There are some important characteristics(特征) that a robot must have. These characteristics might help you to decide what is and what is not a robot. It will also help you to decide what you will need to build into a machine before it can be considered as a robot. A robot has these important characteristics.

    Sensing First of all, your robot would have to be able to sense the environment around it. 

    Give your robot sensors (传感器): light sensors( eyes ), touch sensors (hands), chemical sensors(nose), hearing sensors(ears) and taste sensors (tongue).

    Movement A robot needs to be able to move around its environment.  It can move on wheels, walk on legs or be driven by small engines(发动机). A robot can move either the whole body or just parts of it.

    Energy A robot needs to be able to power itself.  Some robots might power itself with sunlight, some might with electricity, while others with the battery(电池). The way your robot gets its energy will depend on what your robot needs to do.

    Intelligence A robot needs some kind of "smarts". A programmer is the person who gives the robot its "smarts". The robot will have to have a certain way to receive the program so that it knows what it is to do.

    If you look at the top of your phone, you'll usually see a lite symbol that says 3G or 4G. The "G" is the generation(代)" of your mobile network (移动网络). But these symbols will become things of the past after 5G networks fully arrive.

    On March 30, 2019, Shanghai vice mayor (副市长) Wu Qing made the first SG video call on a Huawei Mate x smartphone, CGTN reported. Shanghai has also become the first city in China to start testing 5G networks.

    About 100 times faster than 4G networks, 5G will let people download (下载) and upload data (数据) faster than ever before. But 5G won't just bring faster mobile internet. People can use it for many other things as well.

    For example, 5G will help to make self-driving cars safer. Today's self-driving test cars have one problem-lag (延迟). When the car "sees" an obstacle (障碍物), it sends this information to a data center and receives instructions (指令).

    However, it takes time to send and receive this information. With this kind of lag, the cars might hit each other because they don't receive instructions in time. With 5G, this lag will be greatly lowered (降低), making the cars safer, according to CNN. 5G could also be used to help the internet of things (IoT,物联网). IoT is a large online network that connects all things and people. Fast internet speed will be the key to developing this technology. The IoT could be used in a lot of ways. For example, with IoT, your refrigerator could automatically (自动地) place an order online for eggs when it finds that there are no eggs left inside.