Dragging a sleigh loaded with enough presents for the world’s children can be no easy skill. But, since ancient times, the Christmas Eve duty has been performed by a team of beloved reindeer.

Soon, however, Santa Claus may have to start looking around for a stronger type of animal, as newresearch shows the species is becoming increasingly puny. A 16-year survey on the arctic Norwegian islands, Svalbard, found the reindeer there have declined in weight by an alarming 12 percent.

The reduction in average body weight is being blamed on global warming. In the research presented lately at a meeting of the British Ecological Society in Liverpool, scientists have explained how upward temperatures are robbing female reindeer of nutrients during important periods of pregnancy.

Snow in Svalbard typically covers the ground for eight months of a year, which, combined with low temperatures, limits grass growth to June and July. But as summer temperatures increase by around 1. 5℃, grass has become more productive, allowing female reindeer to gain more weight by autumn and therefore to have more babies. However, winters have brought with them greater rainfall which freezes when it settles on the snow. Reindeer can often access the poor food sources beneath the snow by clearing it away with their antlers (鹿角) , but they cannot break through the hard ice. As a result, female reindeer are becoming starved, causing them to lose their babies or give birth to the much lighter young.

Despite the findings, reindeer appear to be suffering less from the effect of climate change than some other arctic species. Last week the scientists warned that a third of the world’s polar bears could disappear in the next 40 years.

Who is willing to drink the polluting water? It can cause us to be ill but even to die. We can’t wait for the moment to protect our water sources. The water we use coming from the ocean, lakes, rivers or streams. But many of these water sources are getting serious polluted. Towns and cities pump sewage（污水）into the water. Many people are throwing all kinds dirty things into the water. Factories poured waste material into the water. Therefore, water sources have become so badly polluted that some of the water is fit to drink or use it. Now it is high time when we should do something to protect our water environment from being polluted.

   The majority of the people make tree houses using a pile of wood, a hammer, and some nails. Mitchell Joachim, an architect from the Massachusetts Institute of Technology, has a（n）_______ vision（设想）. He _______ a day when homes will be created from living trees.

Joachim’s vision is _______ on an idea called pleaching（编织）, where tree branches are grown so that they _______ weave together. Since the growth patterns of trees are _______ by wind and sunlight, it may be _______ to control the way a tree develops.

These Fabricated Tree House Habitats would use trees grown into shapes as housing. One of the _______ of these designs is that trees would not have to be cut down _______.

“A 100 percent tree house would _______ years to create,” Joachim said. __________ the climate, a house could take anywhere from 5 to 30 years to grow. Fortunately, there’s a way to speed up the __________. Joachim __________ including ecological materials such as grasses and living branches in the housing designs. “This material would be able to move __________ the house grows,” Joachim said.

A home would become an actual ecosystem, a community of plants, animals, and bacteria working together. The trees would also give off water vapor（蒸气）that would assist in __________ the homes. Solar panels and wind would help provide __________. The tree homes might even have soil pockets, where plants could __________ in the structure itself.

Work has already __________ on Joachim’s first design — a house made from 50 percent recycled and 50 percent living things. Joachim is confident about the __________ of his work, as he uses __________ products without destroying nature.

“The environment and its study are very important. We need to __________ nature, and don’t take it for granted,” he said.

Can you imagine wear a pretty sweater made from garbages? It could happen! A few companies across the country are making clothes from things that are being thrown away by people. For example, company makes sweaters of old plastic bottles. First, the bottles are cut into small pieces. The pieces are melted. Then the melting plastic is made into long and thin threads. The threads are used to make sweaters which feels very soft and light.

Believe it or not, these sweaters sell good in spite of the fact which they are not cheap at all. Many people thought that these recycled clothes can help us cut down on garbage.