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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    A large number of women in Western European countries wish that they were born men. The number is said as high as 60% in West Germany. “Women often wish that they had the same chance as men have, and believe it is still men's world,” said Dr James Holden, one of the scientists who did the study.

    Anne Harper has a very good job for an international oil company. She also believes in “Women' s Liberation(解放)”. “I don't wish that I were a man,” she says, “and I don't think many women do. But I do wish that people would stop looking down upon us women. At work, for example, we often do the work that men do but get paid less. There are still a lot of jobs that are usually the best ones and open only to men. If you're a man, you have a much better chance of leading an exciting life. How many women pilots are there ... or engineers or scientists?”

    Over the past few years, smart home tech has become more and more accessible and it's increasingly easy to find that you've bought a product that includes smart home features. So what does a modern smart home look like, and how can you start building one? You could get to start making your home smarter by the following gadgets.

    Ecobee 4

    *Measuring both occupancy and temperature, its sensors signal your Ecobee to automatically switch to the right mode.

    It only takes about 30 minutes, thanks to an easy-to-follow installation guide and an in-app step-by-step walkthrough.

    Easily adjust temperature using your voice with built-in Alexa or from wherever you are using your mobile devices.

    Amazon Smart Plug

    Amazon Smart Plug works with Alexa to add voice control.

    Schedule lights, fans, and appliances to turn on and off automatically, or control them remotely when you're away.

    It's simple to set up and use. Plug in, open Alexa app, and start using your voice.

    The Philips Hue White Smart Bulb

    It works with Amazon Alexa to support dimming through voice control.

    Schedule your own custom lighting scenes. Set the smart bulbs to turn on and off at a pre-set time.

    To install, simply screw(拧) the smart bulbs into your desired light location.

    Control smart-bulb-equipped lamps and overhead lights via the Philips Hue App.

    August Smart Lock Pro

    It works with Alexa for voice control(Alexa device sold separately).

    Control keyless access. It locks automatically behind you, and unlocks as you approach.

    Install in about 10 minutes with just a screwdriver(螺丝刀).

    Grown-ups are often surprised by how well they remember something they learned as children but have never practiced ever since. A man who has not had a chance to go swimming for years can still swim as well as ever when he gets back in the water. He can get on a bicycle after many years and still ride away. He can play, catch and hit a ball as well as his son. A mother who has not thought about the words for years can teach her daughter the poem that begins "Twinkle, twinkle, little star" or remember the story of Cinderella or Goldilocks and the Three Bears.

    One explanation is the law of overlearning, which can be stated as follows: Once we have learned something, extra learning trials (尝试) increase the length of time we will remember it.

    In childhood we usually continue to practice such skills as swimming, bicycle riding, and playing baseball long after we have learned them. We continue to listen to and remind ourselves of words such as "Twinkle, twinkle, little star" and childhood tales such as Cinderella and Goldilocks. We not only learn but overlearn.

    The multiplication tables (乘法口诀表) are an exception (例外) to the general rule that we forget rather quickly the things that we learn in school, because they are another of the things we overlearn in childhood.

The law of overlearning explains why cramming (突击学习) for an examination, though it may result in a passing grade, is not a satisfactory way to learn a college course. By cramming, a student may learn the subject well enough to get by on the examination, but he is likely soon to forget almost everything he learned. A little overlearning, on the other hand, is really necessary for one's future development.

    We spend a great amount of time listening to music. Most college students listen to music at least three or four times a week, and more than 50 percent of them go to at least one concert per year.

    According to new research, we may be born liking music, because human beings are born to find certain combinations of sounds attractive. For example, young children can recognize a familiar Song even when its key is changed. Similarly, they respond with more emotions to their mothers' singing than to their mothers' speech. Careful analysis of mothers' child-directed songs indicates that each mother's songs remain stable from one "performance" to the next, and this may encourage children's engagement with the songs.

    Research with adults suggests that music catches our attention by activating(激活) brain pathways that are most suited to processing music than to processing other kinds of sound. Specifically, music appreciation relies on the auditory cortex(听觉皮层) on the right side of the brain, which is specialized to process sound that characterizes music-in contrast to the left auditory cortex, which processes the stop-and-start bursts of sound that characterize speech.

    Although some Psychologists remain skeptical about whether music may have powerful effects on our thinking, a number of studies have shown that listening to music can increase people's spatial reasoning abilities Furthermore, It is clear that music can greatly influence our emotions. Personally significant music activates areas of the brain associated with pleasure and reward, the same areas that are activated by sex and good food.

    Researchers do not agree about how humans' abilities to process and enjoy music have come into being. Anyway, the next time you enjoy listening to a piece of music, remember that the most complex pieces of audio equipment are the ones between your headphones.

The world continues to inspire travel writers. Standout books for the year ahead are to please all types of our readers.

A Search for Nearby Nature and Wilderness

World explorer Alastair Humphries spent a year examining every square metre of a 12-mile radius (半径) around his home in London and found wonder close to hand. A former Adventurer of the Year, Humphries has cycled around the globe and rowed across the Atlantic Ocean. His latest book, though, is a celebration of slowing things down and discovering a small wild world right on your doorstep. It's also a cry to revitalize London's neglected natural places in urban areas and our right to wander in them. £12.99, Eye Books.

My Adventures in Travel and Publishing

Travel publisher, Hilary Bradt's guidebook company celebrates its 50th anniversary this year. The first Bradt Travel Guide was born in1974: BackpackingAlong Ancient Ways Peru & Bolivia which included some of the very first descriptions of the Inca Trail. Since then, Bradt has published many guidebooks about the farthest parts of the planet — Mongolia and Madagascar among them. Pioneering backpacking travels before the concept was widespread, he presents this book looking back at a lifetime of trials and stimulation in the wild. £20.00, Bradt.

True Stories of Nature, Adventure & Connection

Environmental writer Laurie King has gathered a collection of original non-fiction stories, illustrations, and poems examining the human connection with nature. He takes a walk across the desert and discovers how hermits (隐士) survived in a South American forest. These exciting stories aim to inspire you to find your wild animal soul and rethink your relationship with nature. £14.99, Watkins Publishing.

Writers Walk the World

From the streets of London to the paths of Japan, the jungles of Ghana and beyond, Duncan Minshull collects the works of more than fifty walker-writers who have traveled the world's seven continents on foot. From the 1500s to the present day comes a memorable band of explorers and adventurers, scientists and craftsmen, pleasure-seekers and literary drifters sharing their experiences and asking themselves a question — why travel this way in the first place? £15.99, Notting Hill Editions.