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    In today's world, sleep experts say that for a better night's rest, Americans should turn off their smartphones or iPad before sleeping. Such electronic products make the brain more active, and then influence their sleep. But according to a latest survey, more than 90% of Americans regularly use a computer or some other kinds of electronic products in the hour before bed.

    Researchers are finding that man-made light from some electronic products at night may reduce the brain chemicals(化学物质) that help sleep. The researchers showed that sitting in the light from computer tablets clearly lowered levels of the chemical which manages our body clocks and plays a role in the sleep cycle.

    In the study, the researchers let volunteers read, play games and watch movies on a tablet for different time while measuring(测量) how much light their eyes received. They found that two hours of sitting before a bright tablet screen at night reduced the sleep chemical levels by about 22%.

    Studies of students using computers at night have got the similar results. And researchers say that may not only cause sleeplessness, but also raise the risk of obesity(肥胖症), diabetes(糖尿病) and other diseases.

    To be on the safe side, the researchers advise us to use computers less before bed, or at the very least turning down your screen as much as possible.

Mobike—it's a bike showing network where users search for a ride through an App. Mobike 1in shanghai at the end of last year.2 December 2016, Shanghai became 3 bike- share city in the world. And then Mobike recently expanded to Beijing, Guangzhou and Shenzhen. They are becoming 4 popular, especially among white -collar workers during rush hours. For that reason, a large number of bikes5in the streets. The bike ride's record has reached about twenty6on a single day .

    Mobike is7convenient that the users can find and leave bikes wherever they'd like. The users8 have the company's mobile's APP just need to use their phones 9 the QR code (二维码) on the bike, and then unlock the bike to begin the timer on the Uber-esque .Besides Mobike doesn't use a parking station in the street.Instead, users can10bikes anywhere with the app-controlled smart lock.11 it also means that users sometimes leave them in a bad place where it's hard for12users to find them. To deal with this problem, the founder of Mobike and her team 13on a points-based system to punish unruly rides.

    Sharing  bikes is made to reduce the pressure of traffic.14 it can run well, and the price is kept low, it may be a great15 to protect the environment .

    We cannot stop earthquakes, but we can do things to make sure they do not destroy (破坏) whole cities. First, it is not a 1 idea to build houses along the lines where2of the earth's plates join together. Second, if you think there 3 be an earthquake, it is better to build houses on rock, not on 4. Third, you must make the houses as 5 as possible. Weak buildings will fall down in an earthquake, but strong ones may 6.

    Scientists are 7 that one day an even bigger earthquake will hit the part around S an Francisco. They call it “The Big One”. But people today are still building more 8. The population in and around San Francisco 9 is ten times more than it was in 1906. This means that 10 there is another earthquake, a great many houses and buildings will be destroyed.

    Do you often drink bottled drinks? Of course 1  is so cool to get a cold one right out of the fridge, right? But all those plastic bottles use a lot of oil and  2 the environment. Americans buy 3 bottled water than any other nation in the world. In order to make all these bottles, 17 million barrels (桶) of oil  4up. That's enough oil to keep a million cars going for twelve months.

    Many people choose 5 the bottles away after having the bottled drinks. In fact, instead of going out with the trash, plastic bottles can be turned into carpeting for clothing. Remember this: Recycling one plastic bottle  6save enough energy to power a 60-watt light bulb for six hours.7 , for every six water bottles we use, only one is recycled. The rest are sent as garbage (垃圾). Or, even worse, they end up 8  trash on the land or in rivers and oceans.

    So why don't more people drink water from the kitchen? Some people drink bottled water 9 they think it is better for them, but that's not true. The chemicals in the bottles themselves may get into the water which can do harm to people.

    So next time when you have drinks or water, please  10 to use a glass at home or carry water in a steel bottle. And if you want to do something more, try to collect plastic bottles and send them for recycling.