Have you ever wondered when dogs first became “man's best friend” and the world's favourite pet? If you have then you're not alone. When and where dogs first began living side-side with humans are questions that have stirred hot debate among scientists. There are a few hard facts that all agree on. These include that dogs were once wolves and they were the first animal to be domesticated(驯养) by humans. They came into lives some 15000 years ago, before the dawn of agriculture.

    Beyond that, there is little agreement. The earliest bones found that are unquestionable dogs and not wolves date from 14,000 years ago. However, 30,000-year-old skulls have been discovered in France and Belgium that are not pure wolf and some scientists think could be dogs.

    With such puzzling evidence, many scientists are now turning to DNA to find out when and where dogs were first domesticated. In one research project, tens of thousands of blood samples have been taken from street dogs around the world. The plan is to compare them with those of wolves. It's even possible to analyse DNA from ancient bones. Tiny pieces of the 30,000-year-old skulls mentioned earlier are currently being studied, and another DNA study has already shown that ancient dogs preserved in the Alaskan ice-fields evolved from Asian wolves, not American ones.

    Indeed, the ancient DNA may turn out to be more informative than the DNA of living dogs. Because dogs have accompanied humans around the world for thousands of years, their current distribution may tell us very little of their origins. This is why different groups of scientists believe that dogs variously originated in eastern Asia, Mongolia, Siberia, Europe or Africa.

    But why were the animals domesticated in the first place? The most recent theory is that dogs domesticated themselves, initially living in and around our ancient villages to eat any food thrown out. Today, this is a way of life still shared by three -quarters of a billion unowned dogs worldwide.

    A California wind farm will become the first in the U. S. to avoid charges if a limited number of eagles are injured or die when they run into the huge turning blades(桨叶), the U. S. Fish and Wildlife Service said Thursday.

    The Shiloh IV Wind Project LLC, 60 miles east of San Francisco, will receive a special permit allowing up to five golden eagles to be accidentally killed over five years. Previously, such eagle deaths could potentially draw criminal charges and discourage private investment in wind farms.

    Agency Director Daniel Ashe said the permit encourages development of renewable energy while requiring the wind company to take steps to protect eagles from turbines(涡轮机)and power lines. The move will help California reach its goal of producing one-third of its energy from renewable sources by 2020, he said.

    Michael Hutchins of the American Bird Conservancy said he believes the five-year permit for the California wind farm is reasonable, but he said the rapid expansion of wind energy has gotten ahead of the science and regulation to protect all types of birds. Too often, he said, wind farms are built in migratory patterns or near wetlands.

    Birds on the hunt can become dizzy by what's on the ground and fly into the blades, Hutchins said.

    “Is it really green energy if it's going to kill hundreds of thousands of birds or bats each year?” he said. “The whole system needs a much harder look.”

    Shiloh IV Wind Project is a 102-megawatt wind farm operating since 2012 and made up of 50 turbines in Solano County.

    Shiloh is the first to obtain a permit. Marie Strassburger, the U. S. Fish and Wildlife Service's regional migratory bird chief, said that obtaining one requires a lengthy process, and because this is the first of its kind, officials have carefully made conversation plans with the wind company.

    “It's not a quick, efficient process by any means,” Strassburger said.

    Federal wildlife officials in California, Nevada and Southern Oregon are working on two more applications for five-year eagle permits and one for 30 years, said Scott Flaherty of the U. S. Fish and Wildlife Service in Sacramento. Eagles are not listed as endangered, but they are protected under a federal act.

    Mary Krupa became friends with the grey squirrels during her first week at Penn State,after spotting them running around and idly（漫不经地）wondering what they would look like with tiny hats on their heads.Today, everyone at the university knows her as the "Squirrel Girl".

    Mary started bringing them food,and gradually they began to trust her.She managed to put a hat on a squirrel and take a picture.Thinking that her colleagues could do with something to lift up their spirits,she started posting similar Photos on Facebook.The response Was greatly positive,and before long Mary and her squirrels became an Internet sensation.

    Growing up in a neighborhood outside State College,Mary was always fond of birds and animals around her home,but she didn't interact with people very much.She was later diagnosed with Asperger's syndrome,but the squirrels changed that.The squirrels are actually a good way to break the ice,because I'll be sitting here patting a squirrel and other people will come over and well just start like feeding the squirrels together and chatting about them,"she said."I am a lot more outgoing.

    And in case you're wondering how Mary is able to get the squirrels to do what she wants for her photos,it has a lot to do with food.For example,whenever she wants them to hold or play with something,she puts peanut butter on the prop（道具）,and they'll grab it.But getting to that part took a while.In the beginning,she would throw peanuts up the trees on campus and invite the squirrels to come down and get them,but they hesitated to approach her.She had the patience to earn their trust,though.

    This year,Mary is graduating with a degree in English and wildlife sciences.She wants to be a science writer and educate people on how to preserve the environment.As for her furry friends,Mary plans to stay in the area and visit them as often as she can.

    Google's new camera, called Clips, is a small, smart device. It comes with a case that has a clip (夹子)，but it's not designed to be worn on your clothing. Most interestingly, it uses artificial intelligence to take photography out of your hands so it can capture moments on its own.

    This roughly 2-inch by 2-inch camera, with a three-hour battery life and Gorilla Glass for toughness, is intended for candid moments, like when a child does something cute that may happen too quickly for you to pull out your smartphone.

On board the Clips device, it uses machine learning algorithms (计算程序) to help capture scenes. Those algorithms include face recognition. “Once it learns that there's a face you see frequently, it'll try to get nice photos of those faces,” said Juston Payne, the device's product manager. And they also want it to recognize facial expressions, which involved “training it to know what happiness looks like”. The Google team also trained it to recognize what not to shoot — like when a child's hand is over the lens, or if it is tossed in a dark purse.

    The only way to see the images is by connecting the camera with your phone, as it has no screen for viewing or editing.

    Were people concerned it could seem strange? Yes, Payne admitted. But they said they addressed that by making it obvious what it is. A green light on the front signals that it is on. Besides, unlike a camera meant to monitor your home, it is not connected to the Internet.

    “This product is only possible because of the way that silicon has advanced” Payne said, noting that it was only in the past year or so that they could squeeze the technology down into a device this size. Going forward, we're likely to get more assistance from the artificial intelligence packed into our apps and gadgets.

    A friend is better than fortune. A friend is worse than poison in some cases.

    The two sentences above have opposite meanings and seem to be unreasonable  but they can be explained as follows: the first refers to all good friends who drive us towards good while the second all bad ones who lead us into bad ways.

    My ideal friend is of course a good friend whose goodness is shown below — he has no bad habits  such as smoking and drinking. He lives in frugality (节俭). He studies hard so as not to waste his golden time. At home he honors his parents and loves his brothers; at school he respects his teachers and shares the feelings of his classmates. He treats those truly who are true to him. In a word, he has all the good characteristics that I don't have. I can follow him as a model. With his help I can be free from all difficulties.

    Indeed, if I have such a person as my friend, I shall never fear difficulty and I shall never know the existence of the word "failure".

Do you want to learn the material you're studying—like, reallylearn it? {#blank#}1{#/blank#}One learning theory suggests that if you overlearn, you'll gain the ability to do something without having to think about it — and eventually obtain more knowledge. Here's what overlearning is and how to do it.

What is overlearning?

Simply put, overlearning means studying something even once you're sure you know it. Don't stop reviewing or studying just because you succeeded in memorizing something. {#blank#}2{#/blank#}

The purpose of overlearning is to make the task easy to ensure it is completed to a high standard with no stress. For example, a student wants to pass their spelling test which has 10 words. Knowing about overlearning, she doesn't just memorize each word, but also learns about the origins of each word. {#blank#}3{#/blank#} Similarly, a teacher wanting to learn about teaching strategies might not simply read one book — they may read ten books, watch videos, attend lectures (and maybe even write their own book).

How do you overlearn?

{#blank#}4{#/blank#} For instance, when using the Leitner method, always review all the flashcards you're assigned on a particular day, even if you feel like passing over them because you got them right last time. Repeatedly going over material you know well is the key to overlearning and eventual automatic recall.

Schedule blocks of time in your week for reviewing materials you've already mastered. {#blank#}5{#/blank#} Continually reintroducing familiar ideas to yourself will dig them deeper into your long term memory.