All living things on the earth need other living things to live. Nothing lives alone. Most animals must live in a group, and even a plant grows close together with others of the same kind. Sometimes one living thing kills another, one eats and the other is eaten. Each kind of life eats another kind of life in order to live, and together they form a food chain (食物链). Some food chains are simple, while others are not. But all food chains begin with the sun, and all food chains become broken up if one of the links (联系) disappears.

    All life needs sunlight to live on. But only plants can use sunlight directly (直接). Plants are “factories”. They make food from sunlight, water and things in the soil (土壤) and air.

    Plants feed all other living things. Animals can only use the sun's energy (能量) after it has been changed into food by plants. Some animals feed directly on plants, others eat smaller animals. Meat-eating animals are only eating plants indirectly.

    What about human beings? We are members of many food chains. We eat wheat (小麦), rice, vegetables, fruits and so on. We also eat meat and drink milk. But humans often break up the food chains. They kill wild animals. They also make rivers, lakes and seas dirty. When these rivers, lakes and seas are polluted, the fish in them cannot be eaten. If men eat the fish, they will get strange diseases (疾病).

    Each form of life is linked to all others. Breaking the links puts all life in danger.

    Sometimes people cry when they are sad. Other times people cry tears of joy. But your eyes make tears all the time, whether you are crying or not. Do you know the tears help keep your eyes healthy? They keep your eyes from drying out. A special area of the eye drips (滴) all the time. It keeps the eye humid.

    If you look in a mirror, you can see tiny holes in the comers of your eyes. Each hole leads to a small tube that runs to your nose. Tears run slowly into this tube drip by drip. Day and night the holes drain (流走) the tears away. If they didn't, you would always look as if you were crying.

    If you begin to cry, there are many more tears. The holes can't drain all of them. Then extra tears run out onto your face.    

    Tears help keep eyes safe. If there is something harmful in the air, the eyes fill with tears. These tears coat your eyes. They keep the harmful air out.

    Contact lenses(隐形眼镜) can make the eyes too dry. Some people have to add tears to their eyes. They buy bottles of eye drops to keep their eyes wet.

    Are you a big fan of E. T. (Extraterrestrial) or aliens? Then you should read Extraterrestrial Civilizations (《地球以外的文明世界》) by American writer Isaac Asimov (1920~1992). In his 1979 book, Asimov looked at whether there is life beyond the Earth. He also talked about how we might be able to communicate with aliens someday. Asimov even told us that there are possibly about 500, 000 civilizations (文明) in the galaxy(银河系). The book may be a little out of fashion since it came out in the 1970s. But you'll still enjoy the good reasoning (推理 ) and imagination of it. Asimov was a science fiction(科幻故事) master. His most famous works talk about the relationship between robots and humankind.

Jin Ying, 25, is a lover of Traditional Chinese Medicine（TCM）. She took part in a three- month training course on acupuncture and tuina（针灸推拿） in the winter of 2023 at Beijing University of Chinese Medicine. 

Jin's life has been different since the training. She changed her life habits after learning the Five Elements theory（五行学说）. For example, she avoided sweating（流汗） too much during exercise in winter because the cold of winter means people should slow down , according to TCM. For her, learning these skills and theories was not about becoming a TCM doctor but rather about embracing（拥抱）a new lifestyle. 

She is not an unusual example of young people becoming interested in TCM. A survey by China Youth Daily showed that 93. 3 percent of the 1, 000 young people who took part had tried different TCM treatments. 

"I have seen a rising number of young people come to me for neck and back pains. which are usually related to the elderly, " said Ma Huifang, a TCM doctor at Guoyitang, a TCM hospital affiliated（附属） with Beijing University of Chinese Medicine. 

Between Western medicine and TCM, young people often choose TCM due to its efficacy（疗效 ）, according to Ma. Some people question why TCM treats the same illnesses with different prescriptions（处方）. "This. is actually an advantage of TCM, rather than a shortcoming, as it can be a more accurate treatment（精准的治疗） for different patients, " Ma explained. 

Younger age groups are embracing TCM, and, at the same time, TCM is also benefiting young people. As Jin noted, "It helps young people understand Chinese medicine and learn why it is believed to be a treasure of our Chinese culture. "