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.

Question: I have recently got a senior position within my company．One of my new tasks is to make monthly progress reports on my department in front of other senior officials. During my first meeting, I presented and then opened the floor to questions．{#blank#}1{#/blank#} My first reaction was to answer defensively(防卫地;戒备地)．Later, I realized that I shouldn't have felt that way．But how can I keep cool and effectively answer questions in this type of settings?

Answer: Congratulations on your new position! Presenting in front of your peers (同事) is a hard task in itself and it becomes much more difficult when a question-and-answer period is required! Question-and-answer periods are a great way to clarify (使……清楚) the message and strengthen key points．{#blank#}2{#/blank#}

●{#blank#}3{#/blank#}

    When a person is asking a question, show interest and a desire to understand the question by listening and asking for clarification.

● Buy time

    When facing a hard question, most people can't give an answer immediately．Buy time by repeating the question in your own words．{#blank#}4{#/blank#} These techniques allow you to quickly organize your thoughts as well as to make sure you will be correctly answering the question.

● Suggest a private meeting.

    A one-to-one meeting is a calmer setting than speaking in front of your peers. {#blank#}5{#/blank#}

A．Show your true interest.

B．Restate the question with respect.

C．Some ideas can be quite concrete.

D．There were many difficult questions.

E．It can also be more effective in exchanging ideas.

F．You may also ask for clarification on the question.

G．Here are some ideas that can help prepare for your next meeting.

    Is your school good for the environment?

    Being green wasn't easy for Kermit the Frog(a famous cartoon character)—but it is for a growing number of schools around the country.A "green" school is an environmentally friendly building that uses less energy by depending on earth's natural resources for heat,light,and power.Green schools have clean air,a lot of natural light,and renewable power sources.

    New studies show that green schools are not only good for the environment,but good for you too!Kids in classrooms with a lot of daylight scored 25 percent higher on reading and math tests than students who studied in rooms with less natural light.Students in schools with more natural light took three to four fewer sick days than students exposed to artificial classroom lighting.The further study found that those students had less dental decay（龋齿）because they were exposed to more of the vitamin D produced by the sun.

The Willow School in N.J. is a school that was built as a green building in 2002.Parts of the building are made wholly from recycled materials.To help trap heat,for example,building workers filled the walls with material from old blue jeans instead of the traditional insulation（绝缘物）made of chemicals.Every classroom has skylights to allow most sunlight,and solar panels（太阳能电池板）line the south end of the building.It uses about 70 percent less energy than a non-green school.This helps the school cut down on high energy costs.

    Kate Burke Walsh,head of the Willow School,says,"Sunlight has an impact—you're happier."The clean,natural surroundings help both students and teachers "handle stress and stay relaxed and focused…it's a very calming atmosphere."

    The health of millions could be at risk because supplies of medicinal plants are being used up. These plants are used to make traditional medicine, including drugs to fight cancer. “The loss of medicinal plants is a quiet disaster,” says Sara Oldfield, secretary general of the NGO Botanic Gardens Conservation International.

    Most people worldwide rely on herbal (药草制的) medicines which are got mostly from wild plants. But some 15,000 of the 50,000 medicinal species are under threat of dying out, according to report from the international conservation group Plantlife. Shortages have been reported in China, India, Kenya, Nepal, Tanzania and Uganda.

    Over-harvesting does the most harm, though pollution and competition from invasive species (入侵物种) and habitat destruction all contribute. Businessmen generally harvest medicinal plants, not caring about sustainability (可持续性),” the Plantlife report says, “damage is serious partly because they have no idea about it, but it is mainly because such collection is unorganized”. Medicinal trees at risk include the Himalayan yew (紫衫) and the African cherry, which are used to treat some cancers.

    The solution, says the report's author, Alan Hamilton, is to encourage local people to protect these plants. Ten projects studied by Plantlife in India, Pakistan, China, Nepal, Uganda and Kenya showed this method can succeed. In Uganda, the project has kept a sustainable supply of low-cost cancer treatments, and in China a public-run medicinal plant project has been created for the first time.”

    “Improving health, earning an income and keeping cultural traditions are important in encouraging people to protect medicinal plants,” says Hamilton, “You have to pay attention to what people are interested in.”

Ghillean Prance, the former director of the Royal Botanic Gardens at Kew in London, agrees that medicinal plants are in need of protection. “Not nearly enough is being done,” he told New Scientist. “We are destroying the very plants that are of most use to us.”

    When we see a person in trouble, the first idea that comes to our mind is to lend a hand. But what if we see an animal in trouble, does the same rule apply?

    This question was raised after a group of penguins were saved from an icy gully (峡谷) in Antarctica. It was filmed for the BBC wildlife series Dynasties. The film crew were anxious when they saw that a group of penguins had fallen into a gully and been trapped with their young. They built a slope (斜坡) so that a few of the penguins could save themselves.

    The case has taken the international media by storm. Viewers watching this film let out a sigh of relief. "I'm so glad. I understand not taking action directly, but a helping hand isn't bothering, right?" viewer Kathryn Shaw said on her Facebook.

    However, others think human interference (干涉) is unnatural. "You can't have sunshine throughout your life. To have done anything else would only make matters worse," said the show's creator David Attenborough, according to The Times.

    In this case, however, Mike Gunton, the executive producer of the series, said that this was a one-off situation. "There were no animals going to suffer by interfering. You weren't touching the animals and it was just felt by doing this... they had the chance not to have to keep slipping down the slope," he told the BBC.

    Such cases are familiar to Paul Nicklen, wildlife photographer for National Geographic. He told Metro, "If it's ever a predator (捕食者) situation, no matter how gut-wrenching, you stay out of the way. Even when you're watching a male polar bear eat a baby bear."

    "There's no rule book in those situations. You can only respond to the facts that are right there in front of you," Will Lawson, the show's director, told Daily Mail.