People depend on plants. We use plants for food, cloth, shelter (住处), and even the air we breathe (呼吸).

    Plants keep our air and water clean. Green plants give us oxygen (氧气). Oxygen is part of the air we breathe.

    Plants are also part of the water cycle (水循环). Most of the water that a plant takes in goes back into the air.

    Plants give us a lot of the food on the earth. Fruits, vegetables, and grains (谷物) come from plants. Without plants, we would not have bread, rice, carrots, apples, oranges, or bananas! Many people are growing plants to eat in their own gardens at home. Having your own garden helps the earth as well.

    When you grow your own fruits and vegetables, you help cut down on pollution because big trucks don't need to take your food to shops. You also help reduce the amount of rubbish because you don't need to use bags for packing your food. You can just pick it out of the ground or off a plant and put it into a basket!

    Trees are an important plant resource (资源). Trees provide wood to build homes and furniture. Trees are used to make lots of things around your home and at your school. And trees provide fruits that are good for you. Without trees, the earth would be a very different place.

    It's a common belief that fish can't remember anything for longer than seven seconds. It may seem sad to think that every moment in their lives would be like seeing the world for the first time. But don't be so quick to feel sorry for them. A new study has found that fish have much better memories than we used to think.

    In the study, researchers from Mac Ewan University in Canada trained a kind of fish called African cichlids to go to a certain area of their tank to get food. They took the fish out and then waited for 12 days before putting them back in the tank again. They found that after such a long break the fish sill went to the same place where they first got food.

    In fact, scientists had been thinking for a long time that African cichlids might have a good memory. But there was no clear evidence until the latest findings.

    Just as a good memory can make our lives easier, it also plays an important part when a fish is trying to survive in the wild. "If fish are able to remember that a certain area contains (容纳) safe food, they will be able to go back to that area without putting their lives in danger," lead researcher Trevor Hamilton told Live Science.

    So next time you are watching your pet fish from outside the tank, perhaps you should feel close to them-they may remember who you are.

    What's going to happen in the future? Will robots control our planet? Will computers become smarter than us? Not likely. But here are some things that scientists say are most likely to happen in 10-30 years from now, according to the BBC.

    Bionic (仿生的) Eyes

    They are no longer something, only in a science fiction movie. People who are blind may have a chance to see things clearly—by wearing bionic eyes.

    A blind eye can no longer sense sight, but a bionic eye can use a camera to "see" the environment and send information to the mind. Now the bionic eye only allows patients to see lights and unclear shapes. A bionic eye with very clear pictures could be just in a few years away.

    Digital Money

    We used to pay with cash for everything we bought. Now we can use Wechat Pay or Alipay to shop, money is spent without seeing it. That means we are already using digital money. People only need to take a mobile phone wherever they go. Using these ways is much easier than searching our pockets for change. It is also safer than carrying a lot of cash.

    It is reported that people in Sweden completely stopped using cash last year, and the US might be the next.

    Self-driving Cars

    Unlike a human driver, a self-driving car won't be influenced by a phone call, the radio or something outside the window. Sensors (探测器) and cameras on the car would allow it to follow the rules of the road strictly and keep a safe space from other cars. This would greatly make the number of road accidents smaller. You can even take a short rest while the car drives itself. In the future, driverless cars would be widely accepted.

    When Sally was a child, she went to the city park with her mom on a sunny morning. She felt very unhappy. Her mom saw that and asked why. Sally told her mother that she felt so sorry to see so much rubbish on the ground.

    Her mom looked around. There were pieces of paper, boxes, glass bottles and a lot of other rubbish everywhere. "What can we do? " asked Sally sadly. "I'm sure you will think of something," said her mom.

    As soon as Sally got home with her mom, she painted a picture of the park and wrote a sign in large black letters at the top of the picture. The sign said, "PLEASE KEEP OUR PARK CLEAN". Later, she took plenty of bags and went back to the park with her mom. Sally put up her picture on a big rubbish box.

    The children at the park ran over to see what was going on. Sally handed each of them a bag. "Let's clean up this place," said Sally. Then they began to pick up the rubbish, talking and laughing. Soon, all the bags were full.

    Then Sally's mom led them to put the rubbish into different kinds of rubbish boxes. When they looked at the clean park, they all had a strong feeling of satisfaction.

    From then on, Sally has been keeping doing the cleaning and sorting (分类)rubbish. More and more people joined her to play a part in environment protection.

    Part of Earth's beauty comes from its oceans. Ocean scientists study the chemical make-up of the ocean, weather patterns, the geography of the ocean floor, and many other areas. Their work is exciting, although sometimes dangerous. Using technology to do certain tasks helps. For example, robotic arms are used for very dangerous tasks.

    One basic part of ocean study is understanding waves and how they work. Wind is the great maker of waves. The waves we know are mostly produced by winds blowing over the sea. They are directly connected with the wind speed and the time that wind lasts.

    Sometimes ocean life can be seen in the wave. Living things seem to be staying within the wave, moving slowly inside it as if they were weightless. Besides the beauty of waves, scientists are interested in their technical ways. The diagram of waves shows how scientists examine waves. Waves are measured (测量) from the top (crest) to the bottom (trough). This allows scientists to find out the height of a wave. They also measure waves from crest to crest to determine (测定) the length of a wave.

    During serious storms, huge waves migh cut a sea ship apart. Ships are at great risk of winding up as broken pieces after being hit by the force of a huge wave. By understanding the ocean, scientists can prevent this breakup of ships by predicting when the water will be too dangerous for people and their ships. The study of waves and the ocean also allows scientists to make sure how certain beaches were formed. By studying the oceans, a great deal can be learned about the surface we live on.

    I think there are several reasons that suggest developing robots is a waste of money.

    In San Diego recently $325,000 was spent on inventing a robotic squirrel to do some scientific experiments. The research proved that squirrels are able to scare away snakes by wagging (摇动) their tails. Do you need a robotic squirrel to work this out?

    What about AIBO, a robotic pet, developed in Japan? In Japanese aibou means “buddy”. These pets have been developed at huge cost mainly to provide entertainment. They've been used in movies and music videos. Universities have used them for educational purposes. However, in 2006 the company stopped producing these robotic pets in order to save money. Was it worth a lot of money?

    Then there's NAO, a robot which has been developed by a French company. Its main purpose is to make life easier for humans. It speaks 19 languages and has its own personality. It can tell children a story, help in the classroom or the home, or act as a companion to those people who need someone to be with. A fully developed one costs $16,000. Is that value for money? Who can afford it anyway?

    There may be good reasons why it is worth developing robots, but so far I haven't thought of any.

    We always think that it's OK for us to leave our plants home during our vacation as plants won't scream like pets, right?

    A recent study done by a group of scientists at the Tel Aviv University has discovered that some plants will scream when they are under stress.

    The research was carried out on tomato plants and tobacco plants by cutting their stems (茎) and depriving (剥夺) them of water. A microphone was placed 10cm away from them. When their stems were cut, the plants started "screaming" between 20 and 100 kilohertz, and the scientists guess that this scream is probably meant to warn other plants nearby.

    When the tomato plants' stems were cut, 25 ultrasonic (超声的) pain sounds were recorded in an hour, and at the same time, 15 ultrasonic pain sounds were recorded from the tobacco plants. When they were deprived of water, the tomato plants recorded even more pain sounds with 35 pain sounds in an hour while the tobacco plants recorded about 11 pain sounds.

    The plants also acted differently to different kinds of stresses. For example, the tobacco plants gave out a stronger "scream" when they were deprived of water than when their stems were cut. But plants that were in no immediate (立刻的) danger gave out less than one ultrasonic sound per hour.

    The group of scientists said that plants are not as quiet as we had always thought, but in fact their voices are so high-pitched that we just can't hear them.

    Last year, another study has found out that plants feel pain when they are touched or hurt and they will give off a terrible smell.

    Mona Island is an amazing place to take a vacation. Some of the animals living there can't be found anywhere else in the world. There are fascinating beaches and caves to explore (探险). The sea around the island has colorful fishes.

    Mona Island is very small. The government of Puerto Rico (波多黎各) takes care of the island and has made it a natural reserve. That means the island's animals and plants are protected from being harmed by people. Mona Island is different from most places because people are not allowed to live there. Only a few park workers are able to stay.

    The park workers' job is to keep Mona Island safe and wonderful. Rules must be followed on the island. One rule is that only 100 people at a time can visit the island. That way, the park workers can make sure the land and animals remain safe.

    On the island, visitors can go to see Mona Island iguanas (鬣蜥) which live only on Mona Island.

    Also, visitors can come to the island to have a close look at many kinds of fishes. They can dive(潜水) far below the surface. They use special tools to be able to breathe under the water. Through the clear water, visitors can see the bright colors of the fishes.

    Visitors can also explore caves. Some of the caves even have paintings on the walls. These paintings were made by some Indians who lived on the island hundreds of years ago.

    After a full day of fun activities, visitors can take a rest, listen to the night sounds, and watch the stars in the huge sky. The stars are easier to see. Visitors say that watching the stars is amazing. It's the perfect end to a perfect day.

An Experiment Report on Growing Potato Plants

Things prepared：

a potato that has sprouts

a flower pot with soil

a camera to record progress

Observation：

Day One

    The color of the soil looks darker because I have just watered it. In the center of the pot, I can see a tiny sprout that has grown from the potato under the soil. I'll call it Buddy. Buddy is green and yellow. I wonder how fast it will grow.

Day six

    Without much change in the past six days, I finally see some new progress on Buddy as it has grown taller. It's exciting to see new life like this. I hope Buddy can grow faster.

Day Eleven

    Buddy is getting larger! Three more new sprouts have grown around Buddy! Green leaves have grown on the new sprouts, but they have not fully grown yet. I guess I need to be a bit more patient.

Day Thirteen

    Buddy continues to grow taller. The leaves on the new sprouts have grown a bit. I'm also excited to see more new sprouts that have grown from under the soil.

Day Fifteen

    Finally, the leaves on the other sprouts are 3 cm tall. They're so green. I hope they will soon grow into new potatoes.

What I have learned

    It's really interesting to grow potatoes. During these fifteen days, I have learned that growing potato plants needs plenty of water. If soil is dry, the potato will fail to grow. I have also learned that the temperature needs to be right. If it is too cold, it won't grow.

    I feel that growing plants is just like trying to succeed with anything in life it takes not only time, but also lots of efforts and patience.

    How do you feel about nature? After spending hours indoors, do you feel better when you visit your local park? Most people think that nature is good for our bodies and brains. However, humans are spending more time inside and less time outside. For example, the number of visitors to Canada's national parks is getting lower every year. And in countries such as the USA, only 10% of teenagers spend time outside every day. Many doctors feel that this is a problem in the twenty-first century.

    As a result, some doctors are studying the connection between nature and health: one example of this is the work of Dr Matilda in Sweden. The doctor gave people a maths test. During the test, their heart rates (心率) were fast. After the test, one group of people sat in a 3D-virtual-reality (虚拟现实) room for fifteen minutes with pictures and sounds of nature. Their heart rates were slower than people's in the other group.

    The virtual touch with nature helped them feel more relaxed. Another good example of how nature is good for health comes from Canada. In Toronto, researchers studied 31,000 people living in the city. In general, they found that healthier people lived near parks.

    Because of studies like these, some countries and cities want nature to be part of people's everyday life. In Dubai (迪拜), for example, there are plans for a new shopping mall with a large garden so shoppers can relax outside with trees, plants and water. In Switzerland, "forest schools" are popular. Schoolchildren study their subjects in the forests and do lots of exercise outside. And South Korea (韩国) is another good example: it has new forests near its cities and around 13 million people visit these forests every year. So after building cities for so long, perhaps it's now time to start rebuilding nature.