Lots of people have trees to look at from their bedrooms, but my perspective is different. My name is Miranda Gibson. I have been living at the top of a tree________60 meters for 449 days now. Some people might wonder________on earth I would choose to do this.

Stretching out below me is one of Tasmania’s last areas of ancient forest — in an area that was proposed for World Heritage protection, yet remains under the________of industrial logging. On 12 December 2011, machinery rolled into the forest and the destruction began. I couldn’t________the thought that these forests would be________forever. So, on 14 December 2011, I packed up my life,________of my job plans, and climbed 200 feet onto the top of this tree. I have been here ever since.

People often ask me what I do up here all day. It's busier than you would imagine. Like an office job, but with a splendid________! I spend my days writing about this forest and its urgent need for________on my blog.

Life in the treetops can be________at times. I have times when I feel frustrated and wish I could________, to anywhere, just to have a change of scenery for a minute! There are also times when I feel terribly________. I miss my friends and family. My only connection to the outside world is my phone and computer, which I charge via solar panel.________these times, I find myself loving the experience. Living on the tree has been inspiring. I am willing to________up here for as long as it takes, but I honestly hope it won’t be too________before I will be able to get down and put my feet on the ground in a forest that is no longer under threat — in a forest that will be________guarded for future generations.

In 200 Years Cows May Be the Biggest Land Mammals (哺乳动物) on the Planet

Around 13,000 years ago North America had a wider variety of mammals than modern Africa. There were multiple horse species, camels and some now-extinct animals. And such _________ creatures were not just found in North America. On every continent mammals on average were a lot larger from around 2.5 million until about 11,700 years ago.

Scientists have long debated what caused all these large creatures to go extinct while many of the smaller ones _________. A team of researchers led by biologist Felisa Smith analyzed evidence from millions of years’ worth of mammalian extinctions and found that on each continent large mammals started to _________ around the same time humans first showed up.

If the extinction trend continues, many more large mammals will soon disappear as well, as the primary threats from humans have _________ from overhunting to indirect processes such as habitat loss. The largest land mammal 200 years from now could well be the domestic cow, Smith’s research suggests. In their new study Smith and her team analyzed a database of all land mammals that lived from 65 million years ago until today. “We found _________ no effect of climate on mammalian extinction over 65 million years,” she says. But starting around 125,000 years ago and continuing until today, large mammals have been more likely to go extinct than smaller ones, the researchers found.

The average _________ of surviving mammals has decreased as a result. And those large-mammal extinctions are tightly coupled with the _________ of humans. For most of mammalian _________ history, an animal’s size was not predictive of its extinction risk. That _________ only appeared once humans began to live alongside large mammals.

This finding does not mean climate-related changes could not have __________ some wildlife populations, enabling humans to more easily bring about their eventual downfall. __________, it suggests the greater likelihood of large mammals going extinct is tied to human activities. The animals that evolved without the risk of hunting from humans were suddenly faced with a new __________. They simply could not __________ fast enough to survive the invasion of humans.

Smith says the lesson to be learned from the new findings is that our ancestors prepared us to be extremely skillful killers. “What’s __________ now,” she says, “is that some of us are comfortable enough, have a high enough standard of living, that we can start thinking about our use of the Earth.” Rather than simply behaving as __________, many of us are now in a position to become environmental protectors.

My childhood is closely associated with the Yellow River. My father ______ to take me with him on his trips to Longyangxia Reservoir. At Longyangxia, I was ______ by the beauty of nature and as a child, I wanted to stay there and ______ up with the Yellow River. Li Bai, a poet of the Tang Dynasty, praised the ______ water of the Yellow River. He saw it as coming down from heaven and ______ the people living on the banks of the river. However, in 1997, for about 330 days, not a single ______ of water from the Yellow River went into the sea. ______ are not the only punishments given by nature. A friend of my father, a university professor, is doing ______ on the Yellow River. According to him, since there is no longer enough water to ______ the mud, the river may soon change its course ______ we allow this situation to continue. This is the ______ of unbalanced growth. If we’d taken care of the vegetation in the upper and middle ______ of the river, we would still be able to ______ it as Li Bai described it.

In fact, people have begun to ______ the problem. I have seen farmers _______ trees on mountain slopes in Shanxi province. I have seen them ______ up the hillsides carrying heavy buckets of water collected several kilometers away down in the valley to ______ around the trees. These farmers are ______ helping our Yellow River, just as the river has helped them. These unsung heroes gave me the confidence that with hard work of us all, we and nature will grow together, and ______ in the future, we will be able to drink the ______ water from the Yellow River-our mother river.