Traveling（旅行) is one of the most important activities and people were interested in it many years ago. Modern traffic develops(发展) fast, so traveling to different places has become much faster than before.Staying healthy while traveling can make your trip happier. But do you know how to keep healthyduring a trip? The following advice may be useful to you.

    Before leaving

①Wear comfortable shoes, a hat and sunglasses.

②Take some medicine that you need with you. They can be used when you get ill or have other problems.

③Do some exercise for weeks or months before you leave if you plan to do lots of walking or climbing during your trip.

④Prepare（准备） proper (适当的)food. Take bread, biscuits and some fruit for a long time. They don't go bad quickly. Bring meat, fish, eggs, milk and even salads and vegetables for a nearer one.

While traveling

①Be sure not to eat dirty food or bad fruit.

②Have enough time to take a rest during your trip.Itcan help you become more relaxed.

③Tap（水龙头）water is not safe, so drink bottled water and always clean the cover of the bottle.

④Keep food in good condition（状态）. Remember: If you travel with food, keep hot food hot and cold food cold.

    In 1826, a Frenchman named Niepce needed pictures for his business .But he was not a good artist .So he invented a very simple camera. He put it in a window of his house and took a picture of his garden .That was the first photo.

    The next important date in the history of photography was in 1837. That year, Daguerre, another Frenchman, took a picture of his reading room .He used a new kind of camera in a different way. In his picture you could see everything very clearly, even the smallest thing. This kind of photo was called a Daguerreotype.

    Soon, other people began to use Daguerre's way. Travelers brought back wonderful photos from all around the world .people took picture of famous buildings, cities and mountains.

    In about 1840, photography was improved .Then photographers could take pictures of people and moving things .That was not simple .The photographers had to carry a lot of films and other machines. But this did not stop them, for example, some in the United States worked so hard. Mathew Brady was a famous American photographer. He took many pictures of great people .The pictures were unusual because they were very lifelike.

    Photographers also became one kind of art by the end of the 19th century. Some photos were not just copies of the real world .They showed feelings like other kinds of art.

    Do you know the whales in the sea? There are many relatives(亲属) in the whale family and they always live together with whales.

    Few people know dolphins(海豚) are part of the whale family. Dolphins are not fish. They are mammals(哺乳动物). They breathe air, and they have babies and feed them with milk. Dolphins are famous for their wonderful shows. They can jump high out of the water and show turns in the air. These jumps give the dolphins time to breathe.

    Porpoises(鼠海豚) are also in the whale family and are quite like dolphins. But they are different in the size and shape of the mouth. The dolphin's mouth is long and thin, but the porpoise's is short and thick. Dolphins are also more talkative than porpoises. Dolphins make sounds to talk with each other under water. But porpoises do not do this. Both of them are smart and friendly to humans.

    Not all the members of the whale family are friendly. Big whales are much easier to be angry than smaller dolphins or porpoises. An angry whale can be dangerous. Perhaps this helped to create the story of Moby Dick that sank (使下沉) a ship and made all the people on it die in the sea.

    Bioplastic(生物塑料) is a kind of plastic, but it is not the same as normal plastic. Normal plastic is made from chemical materials and takes a very long time to degrade(降解). But bioplastic is good for the environment. It is made by using bacteria(细菌) to process(加工) natural sources like vegetable oils, corn or sugar. It can degrade more easily.

    But there is a problem with bioplastic. The "food" that bacteria eat is what we eat. This means that bacteria are competing against humans for the same resources.

    Now scientists have found a new way to make bioplastic——using two kinds of bacteria and sunlight, according to Newsweek.

    One of the bacteria can use sunlight to produce sugar. The other kind lives in the salty waters of Bolivia. It eats the sugar that the first bacteria produce and then it can produce polymers(聚合物). Polymers are used to create bioplastics. The way the bacteria store polymers is similar as humans store fats.

    The new way to produce bioplastic has many advantages. It is 20 times faster than the normal way we produce bioplastic. Moreover, using these two bacteria saves resources.

    Firstly, producing a lot of bioplastic requires corn and sugar, which are used to feed normal bacteria. And growing corn and sugar needs farmland. But these two bacteria can just use sunlight. The land that is saved can be used to grow food for humans. Besides, this system doesn't need rich land or clean water at all, scientists said to Newsweek.

    The next problem scientists face is that they want to put their lab research into real-world practice. By doing this, bioplastic made with these two bacteria can be widely produced in the future.

    Cars make our lives more convenient. But they can also be a problem. For example, fossil fuel(化石燃料) cars mainly cause air pollution.

    To improve the environment, many countries are developing electric vehicles(EVs，电动车). Among them, China is taking a leading role and has created the world's largest EV market.

    Last year, over 40 percent of the 753，000 EVs sold in the world were sold in China, more than twice as large as the number sold in the United States.

    "Filling up a fossil fuel car with gas(汽油) is more expensive than charging(充电) an electric car, " said Wu Hao, who bought an electric car this year.

    However, there are still some problems. It can be hard to find charging piles(充电桩) and the cars can't go far before needing to be recharged.

    Some of these problems are being solved. In 2014, China had 31，000 charging piles. Now China has the world's largest EV charging network, with more than 167，000 charging piles in total.

    Developing EVs is one of many efforts that China has made to cut down pressure on its environment after the government promised to stop increases in carbon dioxide emissions(二氧化碳排放量) by 2030.

    "As China goes, so will the world's car industry，" the Wall Street Journal said. China has taken a leading role in the world's electric vehicle industry.