Transparent animals let light pass through their bodies the same way light passes through a window. These animals typically live between 

the surface of the ocean and a depth of about 3,300 feet—as far as most light can reach. Most of them are extremely delicate and can be 

damaged by a simple touch. Sonke  Johnsen, a scientist in biology, says, “These animals live through their life alone. They never

touch anything unless they're eating it, or unless something is eating them.”

And they are as clear as glass. How does an animal become see-through? It's trickier than you might think.

      The objects around you are visible because they interact with light. Light typically travels in a straight line. But some materials slow and

 scatter(散射) light, bouncing it away from its original path. Others absorb light, stopping it dead in its tracks. Both scattering and absorption

 make an object look different from other objects around it, so you can see it easily.

But a transparent object doesn't absorb or scatter light, at least not very much, Light can pass through it without bending or stopping.

That means a transparent object doesn't look very different from the surrounding air or water. You don't see it —you see the things

behind it.

   To become transparent, an animal needs to keep its body from absorbing or scattering light. Living materials can stop light because they

contain pigments(色素) that absorb specific colors of light. But a transparent animal doesn't have pigments, so its tissues won't absorb

 light. According to  Johnsen, avoiding absorption is actually easy. The real challenge is preventing light from scattering.

Animals are built of many different materials—skin, fat, and more—and light moves through each at a different speed. Every time light

moves into a material with a new speed, it bends and scatters.Transparent animals use different tricks to fight scattering. Some animals are

simply very small or extremely flat. Without much tissue to scatter light, it is easier to be see--through. Others build a large, clear mass of

 non-living jelly-lie(果冻状的)material and spread themselves over it .

    Larger transparent animals have the biggest challenge, because they have to make all the different tissues in their bodies slow down light 

exactly as much as water does. They need to look uniform. But how they're doing it is still unknown. One thing is clear for these larger animals, staying transparent is an active process. When they die, they turn a non-transparent milky white.

   Mary and her husband Jim had a dog named “Lucky”．Whenever Mary and Jim had friends come for a weekend visit，they would warn their friends not to leave their luggage open because Lucky would steal something from their luggage and he always hid his finds in his toy box in the basement.

    It happened that Mary found out she had breast cancer.She felt she was going to die of this disease.The night before she was to go to the hospital，a thought struck her，“What would happen to Lucky？” “If I die，who will look after Lucky？” Mary thought.The thought made her sadder than thinking of her own death.

    Mary stayed in the hospital for two weeks.Jim took Lucky for his evening walk every day，but the little dog just looked sad and miserable.

    Finally the day came for Mary to leave the hospital.When she arrived home，Mary was so tired that she couldn't even make it up the steps to her bedroom.Jim made his wife comfortable on the bed and left her to sleep.

    Lucky stood watching Mary but he didn't come to her when she called.It made Mary sad.But she felt so sleepy that soon she fell asleep.

    When Mary woke，for a second she couldn't understand what was wrong.She couldn't move her head and her body felt heavy.But panic(惊慌) soon gave way when Mary realized the problem.She was enclothed with a blanket，and with every treasure Lucky owned!

    While she had slept，the sorrowing dog had made trip after trip to the basement bringing his beloved hostess all his favorite things.He had covered her with his love.

    It's been 12 years now and Mary is still living.Lucky? He still steals treasures and hides them in his toy box but Mary remains his greatest treasure.

    Hold your smartphone, smile at the front camera, and click! You get a selfie. There is no doubt that this photo is yours. But if a monkey takes a selfie, does the camera owner have the right to decide how to use it?

    Recently, this question has caused a problem between Wikimedia Foundation, a non-profit organization, and British wildlife photographer David J. Slater.

    In 2011, Slater was visiting a park in Indonesia when a macaque(猕猴) got hold of one of his cameras. “They were quite naughty, jumping all over my equipment,” Slater told The Telegraph, “and it looked like they were already posing for the  camera when one hit the button.” The result was hundreds of monkey selfies. The best of images was a female macaque grinning toothily into the lens.

    This week, the grinning monkey selfie returned to the news when Wikimedia refused Slater's request to take the photos down from Wikimedia Commons, a website that is run by the organization and offers free images.   5

According to Wikimedia, anyone who downloads the monkey selfie, or any of the millions of images on the site, can “copy and use any works here freely as long as they follow what the author says.” The question that arose here was whether Slater, who had not held the camera, set up the shot, or pressed the shutter(快门) button, could be considered the photographer of the monkey selfie. Wikimedia's position on this was clear: as the work of a non-human animal, this photo has no human author who owns the copyright.”

    Only authors of creative works, like a piece of writing or a song, own copyrights. In terms of photos, US copyright law says whoever pushes the button on the camera owns the copyright to the image produced, which means that if tourists ask you to take a photo of them, and you happen to hit the shutter button at the exact moment that Justin Bieber, a Canadian singer, made faces behind them. You, as the photographer, would have the photo's copyright and sell it. The tourists, who own the camera on which the photo was taken and asked you to take the photo don't get the right to use it without you allowing them to. All this has been complicated by the appearance of surveillance cameras(监控摄像头), smart phones, and large-scale photography projects for which assistants often press the shutter button to produce works whose copyrights belong to their boss.

    Slater seems to be thinking along these lines. He says that buying the cameras, spending thousands of pounds to transport himself to Indonesia, and allowing the monkeys to “steal” his cameras makes him the author of the image, regardless of who pushed the button. “In law, if I have an assistant then I still own the copyright,” he told the “Today” Show. “I believe in this case, the monkey was my assistant.”

    If that seems unfair, think about this. If a person left her laptop in a café, and a poet picked it up, opened up a word-processing program, and typed out a poem which turned out to be the best poem of this generation, could she ask for much more than her laptop back?

    When I was a boy there were no smart phones, and our television only got one channel clearly. Still, I never felt bored. The fields, hills and woodlands around my home were the perfect playground whose adventures were only limited by my imagination. I can remember once hiking to nearby lake and walking slowly around it. At the back of it I was amazed to find an old dirt road that I had never seen before. It was full of muddy type tracks and deep woods bordered it on both sides, but exploring it still seemed like a fine adventure.

    I walked on and on for what seemed like hours. I was sure my guardian angel was whispering in my ears "turn around and head back home", but I was stubborn and walked on. There was still neither a car nor a house in sight I noticed that the sun was starting to go down and I grew scared I didn't want to end up trapped on this road, and I was worried that it would be dark before I could make my way back to the lake again.

    I continued to walk on with something growing inside of me. My heart was pounding and my legs were aching. I was almost in tears when I saw something in the distance. It was a house that I recognized. I jumped up and down and laughed out loud. It was still over a mile away, but my legs felt like feathers and I hurried back to my house in no time. I walked in with a big smile on my face just in time for dinner. Then I ended my adventure with a good night's sleep.

    I often thought of that experience recently. Actually, in our life, all roads, no matter how they twist and turn, can lead us home again. They can lead us to our homes in our hearts. May you always walk your path with love! May you always help your fellow travelers along the way! And may your roads always lead you home again!

    Think of a seed buried in a pot. It's dark down there in the potting soil. There's no light, no sunshine. So how does it know which way is up and which way is down? It does know. Seeds send shoots up toward the sky, and roots the other way. Darkness doesn't confuse them. Somehow, they get it right.

    More surprisingly, if you turn a seedling (秧苗) or a whole bunch of seedlings upside down, as Thomas Andrew Knight of the Royal Society did around 200 years ago, the tips and roots of the plant will sense, “Hey, I'm upside down. Look! I. will turn my way to the right direction and do a U-turn.”

    How do they know? According to botanist Daniel Chamovitz, Thomas Knight about 200 years ago guessed that plants must sense gravity. Knight proved it with a crazy experiment involving a spinning plate.

    He attached a bunch of plant seedlings onto a disc. The plate was then turned by a water wheel powered by a local stream at a speed of 150 revolutions (旋转) per minute for several days.

    If you have been at an amusement park in a spinning teacup, you know that because of centrifugal force (离心力) you get pushed away from the center of the spinning object toward the outside.

    Knight wondered, would the plants respond to the centrifugal pull of gravity and point their roots to the outside of the spinning plate? When he looked, that's what they'd done. Every plant on the disc had responded to the pull of gravity, and pointed its roots to the outside. The roots pointed out, and the shoots pointed in. So Thomas Knight proved that plants can and do sense the pull.

    Angel Garcia Crespo is a computer engineer at Carlos III University of Madrid in Spain. His group has invented a new way for deaf-blind people to "watch" TV. The idea for the technology grew out of previous work by his group. The team had already worked on making audiovisual(视听的) materials accessible to people with either vision or hearing disabilities. But the group wanted to help people with both challenges. So they asked some deaf-blind people what would help.

    In addition to relying on their sense of touch to communicate, deaf-blind people can also get and send information with a Braille line. The Braille system uses patterns of raised dots to stand for letters and numbers. A Braille line is an electronic machine with a changeable Braille display. Dots rise up or drop down based on the information sent to the machine.

    Now the new system changes TV signals to data a Braille line can use. "The key to the system is the possibility of using subtitles(字幕) to collect TV information, " Garcia Crespo explains. "Subtitles travel with the image(影像) and the audio in electromagnetic waves we don't see. But an electronic system can keep those waves. "

    First, a computer program, or app, pulls out the subtitles and visual descriptions from the broadcast signal. The system then combines the information and changes both into data for Braille.

    Now another app gets to work, which sends the data out to people's Braille lines on demand. "This is done in real time, in less than a second," Garcia Crespo says. This lets a deaf-blind person "watch" TV as it's broadcast. The system will work with various Braille lines, as long as there's a bluetooth connection available. Now, the system is only used in Europe, and it should soon be available in the US.