Forests have always been useful and important to men who make use of them in many ways. Every day trees are serving man everywhere. Trees supply man with fruits and building materials in the form of wood. Without trees it would be impossible to build houses, boats, bridges and so on. Furniture such as desks, chairs and beds is made of wood. Trees can stop man from the terrible heat. They're also useful in preventing(阻止) good and rich top soil from being washed away during heavy rains. If there were no forests, heavy rains would wash away the rich surface(表层) soil that is so important to plants. The result is that the land will become a desert. There are plenty of desert areas in the world. A long time ago these desert areas used to be very rich areas, but men in the past had no enough knowledge about science of nature, and they cut down too many trees in the area where they lived and never planted new ones. By and by, the rich surface soil was blown and washed away by strong winds and heavy rains. In the end the rich land changed into useless deserts where nothing could grow.

Smog is a big problem in many Chinese cities. But it seems that besides wearing a mask, few of us know what has caused the smog and what to do to beat it. In fact, burning too much coal and oil are the main causes of PM2.5 and smog (雾霾).

    To solve the problem, we should clean our coal and oil or replace them with cleaner energy such as natural gas. We ordinary people can do something to help control smog, too.

    What can we do to help beat the smog?

    Choose to take public transportation. Though many people have their own cars, they had better take public transportation, such as the subway or buses. If the destination (目的地) is not far away, you can also walk ________ ride a bike.

    Call the hotline 12369. You can call the number for complaints and questions about environmental issues. It is run by China's Ministry of Environmental Protection. If you call the number, some officers can come and try to solve the issues, so please remember it.

Report and resist pollutant source. If you find any pollutant source, take a picture of it and post it on your social media accounts. Remember to add “@local environmental departments” on weibo. Payattention to factories that pollute the environment and don't buy products from them.

    Our environment will become better if everyone is concerned (关注) with the environment. This is what we need in the future. So everyone can do something to beat smog.

    MSG(monosodium glutamate谷氨酸单钠) is a food additive(食品添加剂),which has been widely used by many food factories all over the world since it appeared first in Japan in 1909.

    MSG is a substance that is added to some food to improve its taste and color. It is used in foods around the world such as cakes, bread, frozen meat, fish and vegetables. In the beginning, people thought MSG was safe just like salt and sugar. However, in 1968 some people reported they seemed to have bad reactions(反应) to MSG after having had a meal at a restaurant. They included headaches and quick heartbeat . It was also reported that MSG excited a person's brain and caused his death in Japan. Scientists think that MSG may lead to many neurological disorders(神经紊乱). In mice studies done by a university, the result showed the mice didn't want to eat the food including MSG.

    Today many food companies “hide” MSG on food labels(标签) by using different names. If you see “natural flavorings (调味品) ”,“hydrolyzed protein” and  “spices” in a food label, you are probably seeing a hidden way to “report” MSG in a food label. Every time we have a meal in a restaurant, we always feel the food very delicious to taste, but sometimes it is dangerous for our health because some harmful food additives have been added to the food.

    To protect people's health, our governments, from central to local, are taking action to stop factories producing harmful food additives.

    We can express thoughts and feelings and send sounds and pictures on our smart phones today. We also communicate by using programs like Skype and Face Time. We can't send tastes, smells or touch, of course. But scientists in Britain are trying to develop a way for smart phones to do just that.

    Adrian David Cheok is a professor at City University in London. He wants people to experience communication using all of their senses. He said "In the real world, we can open up the glass, open the window. We can touch, we can taste, we can smell in the real world."

    To give users a sense of taste, researchers designed two electrodes (电极）that are placed on the tongue. A chemical process creates different tastes through molecules (微粒)on the surface of the tongue. This chemical process sends electrical signals that convince the brain that a person is tasting something. They have already created sour, salty, sweet and bitter tastes.

    "You put these two silver electrodes in your mouth, you put your tongue in between and then it stimulates electrically your tongue and you get a virtual taste perception in your brain."

    A device(设备）called "Scentee" permits users to have the sense of smell. Scentee plugs into a smart phone and can spray tiny clouds of fragrances, including flowers, fruits and coffee. Professor Cheok says the person speaking can activate the device.

    Scentee holds a container with about 100 different smells. The container must be replaced when all the scents（pleasant smells) run out.

    Birdwatching is a fun hobby. Many people enjoy it every day. You can also enjoy it. Birdwatching does not have to take a lot of time or money. With materials(材料) around your house, you can build a good birdhouse. You can start birdwatching in 30 minutes in your very own yard. It's very easy!

    Materials you will need:

    Milk box        ●Glue        ●Scissors      ●Brown paint        ●Tools for painting

    To build a better birdhouse

    ⒈Clean and dry the milk box.

    ⒉Glue the top of the milk box shut.

    ⒊Cut holes into the milk box for the birds to get into the birdhouse. The size you use will determine which birds use the house. You can cut one hole per side, or two. A good place to cut is about four inches(英寸) from the bottom(底部).

    ⒋Paint your milk box brown. The color helps the birdhouse mix with the tree.

    ⒌Cut holes into the milk box in the bottom of the box to let out any dirty things. Add at least two small holes on the top of the box. The top holes are to let in clean air. Do this after painting, or the paint could fill in your holes!

    ⒍Put the box in a tree. You can see the birdhouse from a window of your house. Now you can watch your birds in any weather!

    The kiwi lives only in New Zealand. It is a very strange bird because it can not fly.

    The kiwi is the same size as a chicken. It has no wings or tail. It doesn't have any feathers(羽毛)like other birds. It has two feet and each foot has four toes. Its mouth is very long.

    A kiwi likes to have a lot of trees around it. It sleeps during the day because the sunlight hurts its eyes.

    It can smell things with its nose. It is the only bird in the world that can smell things. The kiwi's eggs are very big. There are only a few kiwis in New Zealand now. People never see them. The government says that people can't kill kiwi. New Zealanders want their kiwis to live.

    There is a picture of a kiwi on New Zealand money. People from New Zealand are sometimes called kiwis.