Living in the wild can be hard. Finding food and staying safe aren't easy. Each day, animals struggle to survive in their habitats. Not all animals get by on their own. Some animals form a close partnership with other kinds of animals. These pairings are called symbiotic (共生的) relationships.

    In a symbiotic relationship, the animals depend on each other. One animal helps the other meet its needs. Sounds good, right? Not always. Some animals are not very kind to their partners. In some cases, one animal meets its needs but hurts its partner. Take ticks, for example. These insects suck blood to live. To get blood, they attach themselves to other kinds of animals. Ticks can pass germs that cause disease instead of helping their hosts.

    In other relationships, animals don't treat their partners so poorly Both animals benefit from living with the other animal.

    Small animals called cleaner shrimps have found a way of helping fish at coral reefs. As their name suggests, the shrimps clean the fish. They hang out at what scientists call a cleaning station. A fish stops by. Then a shrimp climbs onto the fish and even steps into the fish's mouth. The shrimp uses its tiny claws to pick stuff off the fish's body. That can include dead skin, tiny pieces of food, and wee creatures that can hurt the fish. The fish gets a nice cleaning. The shrimp enjoys a tasty meal offish trash.

    Small birds called plovers are also in the cleaning business. They have big customers—crocodiles. Crocs have long snouts（鼻子）filled with sharp teeth, Cleaning them is tricky. When a croc opens its mouth, the plover hops right in. The croc does not snap its snout shut. Instead, it lets the plover eat small, harmful animals attached to its teeth. The plover gets an easy meal while the croc gets clean teeth.

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EP Portable Heater

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    Suddenly another thought went through Kate's mind like an electric shock. An express train was due to go past about thirty minutes later. If it were not stopped, that long train, full of passengers, would fall into the stream. “Someone must go to the station and warn the station-master,” Kate thought. But who was to go? She would have to go herself. There was no one else.

    In wind and rain she started on her difficult way. Soon she was at the bridge that crossed the Des Moines River, a bridge also built of wood, just like the bridge across Honey Creek. The storm had not washed this away, but there was no footpath across it. She would have to cross it by stepping from sleeper(枕木) to sleeper. With great care she began the dangerous crossing, sometimes on her hands and knees, hardly daring to look down between the sleepers into the wild flood waters below. If she should slip, she would fall between the sleepers, into the rapidly flowing stream.

    At last-she never knew how long it had taken her-she felt solid ground under her feet. But there was no time to rest. She still had to run more than half a mile and had only a few minutes left. Unless she reached the station before the express did, many, many lives would be lost.

    She did reach the station just as the train came into sight. Fortunately the station-master was standing outside. “The bridge is down! Stop the train! Oh, please stop it!” Kate shouted breathlessly.

    The station-master went pale. He rushed into the station building and came back with a signal light. He waved the red light as the train came into the station. It was not a second too early.

    A nine-year-old kid was sitting at his desk when suddenly there was a puddle（水潭、泥坑） between his feet and the front of his trousers was wet. He thought his heart was going to stop because he couldn't possibly imagine how this had happened. It had never happened before, and he knew that when the boys found out he would never hear the end of it. When the girls found out, they would never speak to him again as long as he lived.

    He prayed this prayer, "Dear God, I need help now! Five minutes from now I'm dead meat!" He looked up from his prayer and here came the teacher with a look in her eyes that said he had been discovered. As the teacher was walking toward him, a classmate named Susie was carrying a goldfish bowl full of water. Susie tripped （绊倒） in front of the teacher and dumped （倒） the bowl of water in the boy's lap. The boy pretended to be angry, but all the while was saying to himself, "Thank you. Lord!"

    Now all of a sudden, instead of being the object of ridicule, the boy was the object of sympathy. The teacher rushed him downstairs and gave him gym shorts to put on while his trousers dried out. All the other children were on their hands and knees cleaning up around his desk. The sympathy was wonderful. But as life would have it, the ridicule that should have been his had been transferred （转移） to someone else+—Susie. She tried to help, but they told her to get out.

    When school was over, the boy walked over to Susie and whispered, "You did that on purpose, didn't you?" Susie whispered back, "I wet my trousers once, too!"

    Attractions in New York

    Empire State Building

    Towering over 444 meters into the sky, the building has an indoor and outdoor observation deck on the 86th and 102nd floor, where you can see the overall view of the New York City. The building houses more than 1000 businesses. You can buy your ticket online in advance to avoid waiting .Telephone ： 212-736-3100 Location ： 350 5th Avenue, New York, NY 10118.

    Open Hours： 08:00-02:00

    Central Park

    For more than 150 years, visitors have come to Central Park's 843 green acres in the heart of Manhattan. Since 1980, the Park has been managed by the Central Park Conservancy, in partnership with the public. You can visit the official website of Central Park to learn more about Park happenings and activities and to learn how to help Central Park Telephone： 212-310-6600

    Location: 59th to 110th Street, Manhattan Borough from Central Park West to 5th Avenue, New York

    City NY 10022

    Open Hours： 06:00-23:00

    The National 9/11 Memorial & Museum

    The National 9/11 Memorial & Museum is a place of remembrance honoring those who lost their lives in the terrorist attacks of September 11, 2001. The 9/11 Memorial Museum displays Monumental artifacts linked to the events of 9/11, while presenting stories of loss, sympathy and recovery that are central to telling the story of the 2001 attacks and the consequence. It also explores the global impact of 9/11 and its continuing significance.

    Telephone： 212-312-8800

    Location: 180 Greenwich St. World Trade Center New York City, NY 10007

    Open Hours： 09:00-20:00

    The Metropolitan Museum of Art

    At New York City's most visited museum and attraction, you will experience over 5,000 years of art from around the world. The Met is for anyone as a source of inspiration, and understanding. You can learn, escape, play, dream, discover and connect.

    Telephone： 212-535-7710

    Location ： 1000 5th Avenue, New York City, NY 10028-0198 Open Hours： 10:00-17:30

Anyone keen to view from on high the prosperous cityscape of Guangdong, may soon can do so from the cabin of a flying taxi. On October 13th the Civil Aviation (航空) Administration of China (CAAC) awarded a "type certificate" to the world's first electric vertical take-off and landing (eVTOL)taxi. And the small two-seater, called the EH216-S, was also permitted to fly without a pilot on board.

The EH216-s is made by EHang, a company based in Guangdong. It looks like a large consumer drone with a passenger bubble installed on top. Propulsion (推动力) is provided by 16 small rotors (转子), installed on the tips of eight arms that fold away when the vehicle is not in use, allowing it to park in small spaces.

The CAAC gave its approval after EHang had conducted more than 40,000 test flights, including with volunteer passengers in 18 cities across China. It also monitored the EH216-s to structural analysis and crash tests, and checked its ability to keep flying if one of its rotors fails. Regulators (监管机构) also inspected the wireless network EHang uses to link its flying taxis to a control centre on the ground. That allows backup pilots to land an aircraft by remote control if there is a problem.

EHang says its pilotless eVTOLs will be quieter than helicopters and much cheaper to operate, thanks to the ability to swap out an expensive pilot for a second paying passenger. The firm also thinks that doing away with pilots will make things safer. A computer's attention never swings, and its reaction operate at a high speed. And it is much easier to automate than driving,for there are fewer barriers and unexpected situations to navigate.

EHang has ambitions beyond China, too. It has carried out demonstration flights in Amèrica and Europe with the aim of obtaining type certificates in both markets. But their regulators both have signalled that they will allow autonomous flights only after the vehicles have proved themselves safe in human hands.