A crow(乌鸦) is about twenty inches (英寸) long and black all over. Crows are dirty birds because they live on bad food. Crows eat a lot of waste food. In this way they are more useful to us than any birds. They clean up the dirty things in our streets. Crows are always hungry. They look for food all day, and in the evening you can see them in large numbers flying back to their nests(巢) in the trees. They sleep there at night.

    Crows are much noisier than other birds. Very often a large number of crows will get together on one house and talk. Sometimes they talk together, and sometimes they do it by turns(轮流) like human beings(人类). It is easy to tell(判断) from crow's sound if they are pleased or angry. Perhaps crows talk a lot because they are friendly birds. A pair of crows will live together all their lives, and if one of them dies, the other one becomes very sad and quiet for the rest of its life and some time later it dies too.

    Every living thing on Earth is either a plant or an animal, right? Wrong! Many organisms（有机体）in our world are neither. Some of them float through the air, and some lie hidden in the ground. They do not need sunlight to survive, and if the weather becomes too cold, they can become inactive until conditions improve.

    What are these? They are called fungi(菌类), and you see them almost every day. Many kinds of fungi seem disgusting, such as the green black things that appear on the food which are left too long in the refrigerator. But other kinds are not so bad. For example, the yeast that is used to make bread and mushrooms (蘑菇) are both fungi.

    What makes fungi different from plants and animals? An animal can move around by itself. Fungi get around too, but they don't have feet, wings, or tails. They have to wait for wind or some other outside force to move them. Plants are different from fungi because they have chlorophyll（叶绿素）. It helps them make food from the energy in sunlight. Fungi do not have chlorophyll.

    Some fungi are bad, while others are not. Some fungi cause diseases, such as athlete's foot, which makes feet uncomfortable. Other kinds of fungi can be used to make medicines, which have saved many lives.

    Fungi clean up more than wounds, though. They are the world's first recyclers. Without fungi, our world would be a mess. Since fungi cannot make their own food as plants do, they must get their food elsewhere. Many fungi get their food from dead plants. They break them down and turn them into soil. The fungi get a meal, and the world gets a housecleaning.

    There is a popular belief that goldfish only have a three-second memory. But a 15-year-old schoolboy from Adelaide has just finished an experiment to tell us that it is not true. He shows everybody that the goldfish is smarter than we think.

    "I don't believe that they had a three-second memory because animals need their memory, so they build up over time a knowledge of where the food is," said Rory Stokes, a student at the Australian Science and Mathematics School.

    He did the experiment in a small tank(鱼缸)of goldfish. "I decided to get a bit of red Logo and just feed them next to that. Every day I'd put it in and spread food around it." He said.

    "At first they were a bit scared of it, but by the end of the three weeks, they were actually almost coming before I put the food in."

    After leaving the fish alone for a week, Rory placed the red Logo block in the tank again.

    "They remembered perfectly well," he said.

    "They actually had a time faster than the average(平均)of the three feeds before I left."

    The goldfish showed that they not only could store information, but also had the ability to get it back at a later date.

    Culum Brown, a researcher at Sydney′s Macquarie University, has studied fish behavior for more than ten years.

    He says his studies of Australian native fish show fish are smart animals that know how to avoid enemies and catch food like any other animal.

    "The thing that I really liked about Rory′s experiment is that he not only got that classical conditioning going but the fact that he could get thorn next just to that specific coloured marker. I thought it was really good." He said.

    We want to explore and try to better understand the world in which we live; Space exploration is one of the ways. Through the exploration of space, we can begin to unravel the mysteries of our universe, and to better know our living environment.

    Space exploration provides us with knowledge about the beginning of our solar system, our own planet and ourselves. It also helps answer the questions that have puzzled us for many years. Solar system exploration is important because it is good for us.

    Space technology has become an important part of our daily lives. Some technology uses satellites to communicate. Satellites are also used to examine the changes in the Earth's climate and seas, for weather report and for military. We also use satellites in food production. Because of the use of space technology in crops, fewer and fewer people will suffer hunger.

    The space program provides a chance for nations to work together. The cooperation(合作) promotes peace and understanding between governments and their people. Many governments have taken part in the space technology, including the United States, Russia, Japan, the European nations and India. In the near future, other nations will take part in it. In fact, the United States remains the leader in new space technology.