Do you think you're green? You're a totally modern citizen, aren't you? You keep your bottles and take them to the bottle bank. You have a black bin and a green bin, one for general waste and one for recyclable waste. Your car uses lead—free petrol. You use the same plastic bag every time you go to the supermarket. Maybe you even cycle to work from time to time. You are playing your part; you are green and environment—friendly. Well, I've got news for you:

    YOU ARE NOT DOING ENOUGH!

    If you don't believe me, look at these facts. Trust me, they're from a BBC website.

    On average every person in the UK throws away their own body weight in rubbish every seven weeks.

    Every year, the average dustbin contains enough unused energy for 500 hot baths, 3,500 hot showers or 5,000 hours of television.

    Every UK household produces over one tonne of rubbish every year.

    If all the aluminium drink cans sold in the UK were recycled, there would be 14 million fewer full dustbins per year.

    Just one recycled aluminium can saves enough energy to run a television for three hours!

    At Christmas over 83 square kilometres of wrapping paper is thrown in the bin.

    Almost three billion nappies (used for baby) are thrown away in the UK every year. 90% of these are buried and take hundreds of years to disappear.

    Have I made you believe that you need to do more? No? OK, here are one or two more facts.

    Recycling just one plastic bottle saves enough energy to power a light bulb for six hours.

    Collecting dustbins and cleaning streets costs ￡1. 6 billion per year.

    Surely you must believe me now. You need to do more. The good news is that there is some— thing else you can do.

    We know the mosquito very well. Mosquitoes fly everywhere. They can be found almost all over the world， and there are more than 2，500 kinds of them.

    No one likes the mosquito. But the mosquito may decide that she loves you. She？ Yes，she. It's true that male mosquito doesn't bite（咬） and only the female mosquito bites because she needs blood to lay eggs. She is always looking for things or people she wants to bite. If she likes what she finds， she bites. But if she doesn't like your blood，she will turn to someone else for more delicious blood. Next time a mosquito bites you，just remember you are chosen. You're different from the others！

    If the mosquito likes you，she lands on your body without letting you know. She bites you so quickly and quietly that you may not feel anything different. After she bites，you will have an itch（痒） on your body because she puts something from her mouth together with your blood. By the time the itching begins，and she has flown away.

    And then what happens？ Well，after her delicious dinner，the mosquito feels tired. She just wants to find a place to have a good rest. There，on a leaf or a wall， she begins to lay eggs，hundreds of eggs.

    People can use the phone to talk with others almost anywhere on the earth. But when you use the phone, you don't see the person you are talking with.

    Today some people are using a kind of telephone called the picture phone or vision phone. With it, two people who are talking can see each other.

    Picture phones can be useful when you have something to show the person you're calling. They may have other uses in the future. One day you may be able to ring up a library and ask to see a book. Then you'll be able to read the book right over your picture phone. Or you may be able to go shopping through your picture phone. If you see something in the newspaper that you think you want to buy, you'll go to the phone and call the shop. People at the shop will show you the thing you're interested in right over the phone .You'll be able to shop all over the town and never even leave your room.

    Rik-rrork. That's the sound made by frogs singing at night. You might have thought the noises were just the musical sounds of ure. You probably didn't realize that you were listening to frogs' communicating with one another. These familiar sounds are not random(随意的) but are actually meaningful to frogs.

Being Heard but Not Seen

    Frogs are good at being heard but not seen. These animals have several characters that protect them n predators (捕食者 ). One is their size. Most frogs are small, which helps them hide easily. Many frogs have coloring that allows them to hide in their environment, making it difficult for predators to find them. In addition, most frogs are active at night. So it is difficult for most animals to see them in the dark.

Small but Loud

    Frogs call to tell other frogs where they are. Their voices can be very loud. But when frogs feel the footsteps of a larger animal, they become silent.

    Many of the world's frogs live in rain forests, where there are many different animals calling to their own species (物种 ) in their own ways. Frogs need to call loudly enough to be heard through the noise in order to find other frogs.

Singing with Purpose

      Peter Narins is a scientist who studies how frogs call to one another. He has learned that frogs use their calls to help them tell friend from enemy. They sing the same notes at the same volume (音量 ) each time they call. In addition, Narins has found that frogs of the same species always sing the same patterns (模式 ). These patterns are like a code that is different from other animals' calls and difficult for others to copy. Narins also observed that timing plays a role in frog calls. Many frogs call only at a certain time of night.

More Work to Do

    Scientists want to better understand the purpose of frog calls. Studies continue to explore the details of frogs' unique communication. Being heard but not seen is one way frogs stay safe. The idea that they have found a way to survive in a dangerous world is simply amazing.

    For thousands of years, humans have explored(探索)the Earth. Nowadays, we are exploring space. Astronomers (天文学家) are the modern﹣day explorers, Now, many astronomers are looking for new planets and new places for humans to live in the future. But where do astronomers start looking？

    First of all, astronomers look for a star. That's because our own Earth moves around a star (the Sun). More importantly, it is the correct distance( 距离) from the Sun for heat and light. So when astronomers have found the star, they look at the planets around it. In recent years, astronomers have found nearly 400 new planets with stars. However, many of these planets are either too near to the star or too far away.

    However, if the planet is in a good position, astronomers look for three key things: water, air and rock. Water is important because all life needs water. Humans can drink it and they can also grow plants with water. And plants produce air for humans to breathe and food to eat. Rock on a planet is also important. That's because there is often water under the rock.

    After many years of scrutinizing, astronomers have found a planet that is similar to the Earth. It's Gliese 581g and it's near a star. The astronomers think it has water and rock and the average(平均的) temperature is between -31℃ and -12℃.That's cold, but not colder than Antarctica or the Arctic Circle, for example. Gliese 581g is bigger than the Earth. A year on Gliese 581g is only 37 Earth days instead of 365. But astronomers do not think these are big differences and some of them think Gliese 581g will be a new Earth. However, Gliese 58Ig is twenty light years from the Earth.