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.

C

    Do you have brown hair? Are you taller than other kids your age? These characteristics were decided before you were born. You got your traits from your parents. They passed their traits on to you through genes (基因).

    Genes carry codes (代码) for blue eyes or brown eyes. Genes say how tall you will get and what color hair you will have. You got half of your genes from your mother. You got half of your genes from your father. So you have your own set of genes. Each person gets different genes for each body part. That is why you look like but not exactly like your brother or sister.

    A dominant (显性的)  gene shows up most of the time. Brown eyes are dominant over bluc eyes. A recessive (降性的)  gene shows up less often. Light hair comes from a recessive gene. Dark hair is more common. Look at the eye color and hair color of the people around you. You will see that this is true.

    Genes help to make you who you are. But they don't tell the whole story. Your genes may help you to be fast and strong. But you still need to learn how to run or swim or skate well.

    Noise pollution is doing much harm to our health now. Noise，in fact，is unwanted sound and is a kind of invisible (无形的) killer. More and more students enjoy listening to music very much. When they listen to MP3 players, they like to turn up the volume (音量). Some people love listening to loud music. Furthermore, while watching TV, they keep the volume up. But they haven't realized that the noise is weakening their hearing. In fact, the noise not only influences each member in the family, but also makes a difference to the comfort of neighbors.

    Noise pollution is a source of increasing misery (痛苦) to people in our society. If people are often disturbed by it, they may feel uncomfortable or upset. What's worse, the noise can make people mad sometimes. If a worker works in a printing factory for too long, his/her hearing loss is much faster than a common person working in a quieter environment. So everybody must pay more attention to noise pollution. Generally speaking，the following four types of noise should be watched out for：

    Noise in the street

    Construction site (建筑工地) noise

    Noise at work

    Transportation noise

    I think the local department (部门) should take measures to control the noise levels, but it's everybody's duty to keep a quiet environment.

    Have you noticed the waste bins(垃圾桶) in different colors on the street? Do you often put all the waste in the same bin? It's reported by Changchun Daily that people must do waste sorting(分类)in most places in Changchun at the end of 2019. Waste sorting is a wonderful way to make good use of energy and protect the environment. But do you know how to sort the waste?

    Usually, people should sort their waste into four groups: wet, recyclable, harmful and dry. Different kinds of waste should go into different bins. Wet waste means the things you don't want but pigs can eat, mostly coming from your kitchen. Things that can be used again, such as paper, metal and glass, are recyclable waste. Harmful waste might be dangerous or cause serious pollution, like medicine and batteries(电池). And any waste that's not wet, recyclable or harmful will go into the dry waste bin.

    Different countries are trying different methods to sort the waste. A university in England has invented a smart bin. When people drop their waste into the bin. It can tell what kind of waste it it and sort it correctly. The bin can also compress the waste to make it smaller in size and take up less space. In South Korea, people have to separate their food waste from other kinds of waste and pay for it. The more food waste they throw away, the more they pay. Japan has the strictest rules for waste sorting in the world. For example, plastic bottles and their caps should go into different bins.