阅读下面材料，从每题所给的三个选项（A、B和C）中，选出最佳选项。

Invention 1	These glasses are made from a special liquid(液体). They allow users to adjust the focus(调整焦距) of the glasses until everything is clear. They are designed for children. So they won't buy new glasses every time when their eyesight changes.
Invention 2	The Donkey Bike has a strong steel bar(钢条) running along it. It can carry both a gas can and a pet at the same time when you ride this bike.
Invention 3	This machine looks friendly and is called Little Printer. It can print news headlines, riddles and other things on a roll(卷) of paper. So you can make your own little newspaper with it.

C

    There is good and bad news about the number of trees on out planet. The good news is that there are seven times more trees for everyone than we thought.

    A few years ago, scientists believed that the world bad 400 billion（十亿）trees. However, a new study from Yale University shows that there are around three trillion（万亿）trees. Thatmeans a three followed by 12 zeroes. That means there are about 420 trees for everyone in the world today.

    The bad news is that thousands of years ago, the earth had six trillion trees. Humans cut in half the number of trees on the planet. Take Europe for example, it was a large forest thousands of years ago. Now much of it is cities and towns. And another 15 billion trees are lost each year.

    Dr. Thomas Crowther is one of the scientists from Yale University. He said the new number of trees from their study would change nothing. " The study only shows we need to do more to protect our forests." He said.

    Australia's Great Barrier Reef(礁) is the world's largest reef system. It is over 2,600 kilometers long. The reef is home to many animals: fish, birds, turtles, sharks and even whales. Unfortunately, the reef that all these animals call home is in danger.

    Climate(气候)change, over fishing and water pollution are damaging(毁坏)the reef every year. Coral(珊瑚)reef experts at Australian universities say that if we do nothing to stop it, the coral reef could be destroyed before the year 2030.

    Everyday things like driving cars, using electricity and running a factory give out greenhouse gases into the air. These gases make Earth warmer and warmer. This is a problem for the Great Barrier Reef and other reefs around the world.

    Coral is very fragile, and even a 2-degree increase in water temperature is enough to kill it, according to Ove Hoegh-Guldberg, reef researcher at the University of Queensland, Australia. If the water temperature doesn't go down, the coral dies.

    But it's not only the coral that's in danger. One quarter of all sea life lives on coral reefs.

    If air pollution is not slowed down or stopped, then the water will warm by at least 3 degrees in the next 20 years, according to reef experts in a report from University of Queensland. This would spell the end for the Great Barrier Reef and all its sea life.

    It's every parent's worst nightmare there's a fire in the house, the alarms are beeping, but the children are sleeping on. Now scientists have found a better way to rouse slumbering youngsters. Researchers in the US have discovered that playing a child a recording of his mother's voice is about three times more likely to wake him up than a traditional alarm.

    Writing in the Journal of Pediatrics, Smith and colleagues report how they compared the effects of four different smoke alarms on 176 children aged between 5 and 12 years old, none of whom had hearing difficulties or were taking any medication that affected their sleep. While one alarm featured a high-pitched beep the sort of commonly found in households the other three featured the voice of the child's mother calling either the child's name, giving instructions such as: "Wake up! Leave the room! ", or both. Each child slept in a lab-based room that resembled a real bedroom.

    The results show that vocal alarms appear to be more effective than high-pitched beeps. About 90% of children woke for a voice alarm compared with just over 53% for the traditional alarm.

    “High pitched beeping alarms don't wake up children well at all under about 12 years of age, "said Dr Gary Smith, a co-author of the research from the Nationwide Children's hospital in Ohio, although

he said at present it is not known why. He said it was important to look at developing better alarms.

    Prof Niamh Nic Daeid, director of the Leverhulme Research Centre for Forensic Science at the University of Dundee, said the research found a human voice combined with a low-frequency pulsing tone was far more effective in waking up children than a traditional high-pitched alarm. She also noted that more work was needed to explore whether other familiar sounds, such as a dog barking, might also prove effective in rousing children.

    Bamboo(竹子) is one of nature s most surprising plants. Many people call this plant a tree, but it is a kind of grass.

    Like other kinds of grass, a bamboo plant may be cut very low to the ground, but it will grow back very quickly. A Japanese scientist reported one bamboo plant which grew 1.5 metres in 24 hours! There are more than 1, 000 kinds of bamboo. Bamboo grows almost everywhere in the world, but in Europe, they can't grow.

    Not all bamboo looks the same. Some bamboo plants are very thin. They may only grow to be a few centimetres wide while others may grow to be more than 30 centimetres across. This plant also comes in different colours, from yellow to black to green.

    Bamboo has been used to make many things such as hats and kitchen tools. Because it is strong, bamboo is also used to build buildings.

    Many Asian countries have used bamboo for hundreds of years. They often use bamboo for buildings and supporting(支撑) new buildings and bridges while they are being built.

    In Africa, poor farmers are taught how to bring water using bamboo. These African countries need cheap ways to bring water because they have no money, and their crops often die from no rain and no water. Bamboo pipes(管子) help poor farmers bring water to their thirsty fields without spending much money.