Some animals sleep during the wintertime because the weather can be very cold and it is difficult for them to find food. They can sleep for a long time. This kind of winter sleep is called “hibernation”.

    If an animal moves about a lot, it needs food. Hibernating animals do not need to eat much because they are not moving about. Their hearts(心脏) beat very slowly and they also breathe(呼吸) slowly. They find a place that is sheltered(遮蔽的) from bad weather and where they are out of danger. Their body fat(脂肪) keeps them alive and warm.

    Some animals, such as bears, may wake up from their hibernation on warm winter days and then quickly go back to sleep again when they see the snow is still thick on the ground. When the weather becomes warmer in spring, the animals start to wake up and look for food.

    American researchers have successfully developed a way to clean waste water without chemicals. The technique uses green plants. The tests were carried out at waste treatment centre. The scientists put plants in narrow containers inside a glass building. One end of each container was a little higher than the other end. Waste water was directed down the containers through the plants' thick roots as we expected. The roots absorbed the waste in the water and used it for food. At the same time the plants produced natural gas. The gas could be collected and sold as fuel(燃料).

    Four places in Florida are already using green plants to clean their waste water.

    There are many wetlands in China and some of them have become the world's important wetlands. The Chinese Yellow Sea Wetlands are among them. They are in Yancheng, Jiangsu Province. They are home to many different kinds of animals. The world's largest Milu Deer Nature Reserve is in them. More than 700 Milu deer live freely there. There are not many red- crowned cranes in the world, but every winter you can see some in the Red-crowned Crane Nature Reserve in the Yellow Sea Wetlands.

    The temperature in the wetlands is usually neither too high nor too low. There is a lot of rain and sunshine too. They are really good places for wildlife. Offering(提供) food and home to some special kinds of animals is not the only reason why we need to protect wetlands. Wetlands are important because they also prevent flood. But some people want to change the wetlands to make more space for farms and less space for wildlife.

    Luckily, more and more people are beginning to realize the importance of wetlands and wildlife. Every year, on February 2nd, many activities are held to tell people more about wetlands.

    In the universe, as we know, there is the Sun, the moon, the Earth and a good many stars. Through our geography lessons, we know the Earth goes around the Sun, and the moon goes around the Earth. We have day and night because the Earth keeps turning all the time. When our part of the Earth turns to the Sun, it is day. When our part of the Earth turns away from the Sun, it is night.

    Just because the moon is closer to the Earth than the Sun, it looks much bigger than the Sun. Big things will look smaller when they are farther, and small things also look bigger when they are nearer.

    The Sun is bright enough to give out very strong light. The moon can't give any light at all, but it looks quite bright, too. Why？In fact, the light from the moon comes from the Sun. The moon looks much bigger and brighter than the stars. But actually (事实上) the stars are much bigger and brighter than the moon. They look smaller than the moon also because they are farther away from the Earth.

    There are still many other planets in the universe. But of all these planets, only on Earth there are living things and people can only live on Earth, too. But at 9∶00 am on October 15th 2003,Chinese astronaut Yang Liwei was set up to space. He stayed there for 21 hours. It was the first time for Chinese to get into space.

Recently, a tourist said in a video that there was no hot water on the Huangshan Mountain. Some tourists also complained(抱怨) online that they failed to get hot water for cooking instant noodles since it was banned(禁止) by the scenic area. For a time, "Why doesn't the Huangshan Scenic Area provide hot water for instant noodles?" became a hot topic on the Internet. Many people thought this rule was unreasonable.

Later, the staff of the Huangshan Scenic Area(景区) replied to the question: In order to protect the animals, plants and environment of the Huangshan Mountain, tourists are advised not to eat instant noodles in the area.

Before the rule was made, leftovers(残羹) and packaging materials from instant noodles were often found throwing in the scenic area. These seriously harm the soil and plants. In addition, animals, such as squirrels and birds, may eat these leftovers by mistake, which poses a threat(威胁) to their health.

In fact, eating instant noodles is not banned on the mountain but it is not encouraged, according to a leader of the scenic area. Actually, the ban on sales of instant noodles on the mountain was put in place in 2006.

The staff at the scenic area said, "Tourists can get hot water at the rest area in the scenic area. They are also allowed to bring their own food products such as bread and self-heating meals. For those who do not bring food, the scenic area has supermarkets and restaurants."

This action quickly received understanding and support from the public. "This is necessary. We should follow the rule while enjoying the beauty of nature," one tourist shared his opinion online. "I support the rule, and we should all play a part in protecting the environment."