We have known for a long time that flowers of different plants open and close at different time of day. Yet no one really understands why flowers open and close like this at special times. It is not as simple as we might think, as new experiments(实验) have shown. In one experiment, flowers were kept in darkness. We might expect that the flowers, without any information about the time of the day, did not open as they usually do. In fact, they continued to open at their usual time. This shows that they have some mysterious (神秘的) way of knowing the time.

    Their sense of time does not depend on information from the outside world; it is, so to speak, inside them, a kind of “inner clock”. This discovery may not seem to be very important. However, it was later found that not just plants but also animals including man have this “inner clock”which controls(控制) working of their bodies and their activities.

    Human beings, then, are also controlled by this mysterious power. Whether we wish it or not, it affects such things in our life as our need for sleep, our need for food. And our ability to concentrate(集中).

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    Everyone knows that exercise is important. It makes your heart and body strong. But you need to know the following.

*Get your body ready!

    Before you do any exercise, be sure to warm up for at least five minutes. During warming up, you should stretch(伸展) all parts of your body.

*Exercise enough, but not too much.

    It's good to exercise twice each week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or even three sports that are right for you.

*Exercise at fitness centres.

    There is a lot of equipment(设备) at fitness centres. The equipment will help exercise your arms, legs and other parts of your body to make you fit. Some people buy equipment. But it is very expensive.

*Stop playing when you are hurt!

    If you get hurt when you are doing exercise, don't play again until you are well.

*Don't get thirsty!

    Drink a lot of water when you are playing sports because it is easy to become thirsty.

    April will bring a new product– the Apple Watch into the market. Last week, the watch was firstly introduced by Tim Cook, Apple's CEO. The price of the watch is from $349 to $1,099, depending on its size and whether it is a sports or regular one. Apple engineers and designers have put in a lot of thought and hard work into creating this small screen on your wrist. The sensor(传感器)on the screen not only finds your finger, but also knows the difference between when you are tapping(轻触), and when you are pressing harder.

    The watch also has haptic feedback(触觉反馈). You can send personal messages to your friend —such as drawing a star or a special sign with your fingers, or tapping the watch, say 3 times, and your friend will receive those taps on their wrist.

    Besides telling the time, the watch will use 'Bluetooth' to connect with your iPhone and show calls or text messages that come in.

    According to Tim Cook, the watch may open up a whole new area of applications（应用） that we had never thought of. Some car factories like BMW have developed an app that allows its car owners to open their cars with the watch. A 'Hotels' app may allow you to open the door to your hotel room without worrying about losing the smart-card. And finally, even at the airport—passengers may be able to simply wave their wrist to check into their flight.

    The biggest use of the watch, however, is as your personal fitness coach. The watch can show your pulse (heartbeat) using a sensor at the bottom of the watch. It also has the same sensor as your iPhone, so it knows when you are moving, and also how much you are walking or running. It will remind you if you have been sitting for too long without taking exercise.

    To protect the environment, we are on the way. Here are a few things we can do.

    Unwanted gifts? Give them away!

    Have you ever received a gift that you didn't like? Did you throw it away? If so, you can have another choice now. Two British companies hopes people will give away their unwanted gifts to them. And they will resell the gifts to raise money for the poor. In this way, the gifts can be refused and have a future life. And people can make a difference to the world.

    Wear the trousers that reduce(减少) pollution!

    A chemistry scientist and a fashion designer(时装设计师) have created a new kind of trousers. The trousers are made of a new material which can help reduce air pollution around us. Scientists have tested the material. The result shows that it isn't harmful to human. This new kind of trousers may appear at the market in two years. Professor Ryan said, "If thousands of people wear the trousers, the air quality will be improved."

    Plant trees with Felix

    Felix Finkbeiner, a 14-year-old German boy, is not famous as a child actor but an environment hero. At the age of 9, Felix got the idea that children could do something to protect the environment. So he started a club. Felix soon got support from children all over the world. Some of them have become his good friends. The club has an aim of planting 212 million trees. They have planted over 3.5 million trees all around the world. Felix said, "The answer to controlling global (全球的 ) warming is trees-lots of trees!”

    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.