2 . One day, Ruslan was fishing with his friends when they noticed something wrong. A mother bear was swimming confidently toward an island but her cubs (幼熊) were ________ in the lake. Ruslan and his friends could ________ believe what was happening.

As the mother bear ________ to head straight for the shore, leaving the cubs drowning in water, Ruslan felt he should do something to help. However, Ruslan’s boat did not turn for them, in ________ of the mother bear turning around and ________ them, until she was out of sight. When the fishermen were still wondering how to save the cubs, or if it was even safe to do so, the cubs made their first ________ and swam toward them.

When the cubs closed up aside the boat and tended to ________ in, they couldn’t get strong enough grasps so they kept slipping. ________, Rusland figured that he could use the fishing net, with the help of which the cubs were finally into the ________. The men were ________ that the cubs would attack them, but it was obvious that they were too ________ to do anything but lie down.

Though the mother never ________ to save the cubs, for their survival and the safety of the men, they ________ moved the cubs to the edge of the forest and then sailed away. Their heroic deed was later ________ spread. When asked why they took such a ________, Ruslan said, “It was dangerous, of course. But they are living creatures, just like us.”

5 . For thousands of years, Chinese writers have travelled all over the country to take down notes about the geographical conditions of each city. Among them, well-known Chinese geographer and writer Li Daoyuan, in the Northern Wei Dynasty (386-534), composed his book, Commentary on the Water Classics, after studying the original literary version, Water Classics. He later expanded the river records to 1, 252 from the original 137.

The book is now being studied again by Professor Li Xiaojie and his team from Fudan University. They have been using drawing software and 3D modelling to recreate the waterway situations on a map based on the book description. So far, they have completed research on four rivers.

“Ancient people knew really well how to apply the power of nature to technical considerations,”Li said, giving the example of Qianjin’e, one of the most famous ancient water conservation projects in Luoyang, Henan. In order to lead the river into the city for irrigation (灌溉) in ancient Luoyang, the officials built a canal branch by separating a northwest-southeast river. However, the canal water wasn't enough to support the citizens in dry seasons. To solve that, on the northern side of the canal branch, the officials built a reservoir (水库) and a channel to lead the water to the canal branch, where the waterways would converge and flow together to the city.

In Commentary on the Water Classics, a total of 2, 800 cities are recorded with details. Still, the process of recreation takes much effort. After doing a lot of text analysis and fieldwork, the team has gradually created the model with 3D modelling software based on repeated deductions (推论).

For Professor Li, the book is not only a record of the natural landscape over 1, 000 years ago, but also a detailed description of humanity and culture and a treasure for today’s reference.

6 . Soil creates life from death. The production of more than 95% of the food we eat relies on soil. But this precious resource is eroding (侵蚀) at a global average of 13.5 tons per hectare per year. Instead of nourishing crops, fertile topsoil is washed and blown away, ending up in inconvenient places such as ditches and oceans.

Jo Handelsman and Kayla Cohen try to make readers care about soil in A World Without Soil. Their prologue (前言) takes the form of a letter to the government. With the letter, they hope to make soil management a federal priority. The following chapters cover the basic science of soil as well as the causes and consequences of its erosion. In the last part of the book, the authors turn to possible solutions—many of them simple, and some centuries old. They describe about traditional soil management techniques, including planting diverse crops in rotation (轮种), increasing organic content, ploughing as little as possible, etc. With these techniques, farmers are able to produce rich agricultural production while maintaining deep banks of fertile soil.

Why, then, is fertile soil being allowed to be washed and blown away? The answer, not surprisingly, rests in global capitalism. Farmers' profit is thin, forcing farmers to plant the highest-profit crop from field to field every season. To ensure food security, Handelsman and Cohen urge the world to demand a real top-down change in how agricultural production is managed. "The burden of protecting soil cannot be shifted to farmers and environmental activists," they note. Governments must begin to move towards a model in which farmers are less independent business people growing and selling food, and more government-supported land workers managing both food production and soil protection. This should be the core of agriculture.

Our land and soil are too precious to be destroyed by the market price of crops. We must invest deeply and thoughtfully in our farmers so that they can invest deeply and thoughtfully in the land. This is the future of farming.

Scientists in Peru have discovered the skull(颅骨) of an ancestor of modern-day whales. The fossilized skull is believed     1    (be) about 36 million years old. Researchers say the discovery suggests that the animal lived in an ocean once     2    (cover) Peru’s southern Ocucaje desert.

The scientists reported the skull was in good condition when     3    (dig) up last year. It has a series of long, pointy     4    (tooth), said Rodolfo Salas, chief of paleontology at Peru’s National University of San Marcos.

Scientists say the ancient mammal was a basilosaurus, which is in the cetacean(鲸目) family. The name basilosaurus means “king lizard(蜥蜴)” and the animal     5    (think) to have been about 12 meters long. But it was not a reptile(爬行动物) although     6    (it) long body might have moved like a large snake.

Salas called the animal “a marine monster” that may belong     7     a new species of basilosaurus. “When it was searching for its food, it     8    (sure) did a lot of damage,” he added.

Salas explained that when the ancient basilosaurus died out, its skull likely sank to the bottom of the ocean,     9     it was quickly buried and remained.

“Back during this age,     10     conditions for fossilization were very good in Ocucaje,” Salas said.

10 . Ever wondered how many Tyrannosaurus rex (霸王龙) ever walked around the Earth? The answer is 2.5 billion over the two million or so years in which the species existed, according to a calculation published today in Science. The figure has allowed researchers to estimate just how rare it is for animals to fossilize.

Researchers led by Charles Marshall used a method employed by ecologists studying contemporary creatures to estimate the population of T. rex during the late Cretaceous period.

The team used their estimates of the total range of T. rex across modern North America, combined with their estimates of the dinosaur’s weight, to calculate that, at one time, around 20,000 T. rex would have been alive on the planet. That translates to around 3,800 T. rex in an area the size of California, or just 2 T. rex moving around Washington DC. Calculating that T. rex survived for about 127,000 generations before disappearing, the researchers came up with a figure of 2.5 billion individuals over the species’ entire existence. Only 32 adult T. rex have been discovered as fossils, so the fossil record accounts for just 1 in about every 80 million T. rex. This means that the chances of being fossilized were small.

These numbers suggest that fossils in general are rare, and that many species that were less widespread than T. rex were probably never preserved, says Marshall, who adds, “The fossil record is our only direct knowledge of these past histories of our planet.”

Thomas Holtz, a researcher, says that “we always knew that the chance of any individual becoming a fossil was rare, but we lacked the calculation to figure out how rare”.

But he says it would be good “to see someone ground-truth these kinds of estimates against living species to get a better sense of accuracy”. He’d also like to see comparable studies made on disappearing species with more abundant fossils, which might allow us to better understand historic ecosystems.