【推荐1】If you go out to the fields at night spring or summer, you can hear singing    1    (happy)here and there. It seems as if they were performing a field concert.

The frog is a beneficial creature that does good to human beings. They can catch fast-moving insects. Each frog eats a large number of pets that are harmful to crops. This little creature is regarded     2    the natural enemy of pests.

But now the number or frogs    3    (become)smaller and smaller. This is    4    they are killed and put    5    the table as a delicious dish by their chief enemy, human beings. It is cruel, isn’t it? The cause of the rapid    6    (reduce)of frogs is that farmers use pesticide(杀虫剂)to kill pests ,and then frogs get     7    (kill)as a result of eating the poison-killed insects.

Something must be done without delay    8    (save)frogs. If we don’t punish those     9    sell and kill frogs to make money, then one day all of us     10    (punish)by nature for failing to save frogs.

Wild elephants that had been roaming the southern Chinese province of Yunnan for more than three months returned to a “more appropriate” habitat, Chinese experts told Xinhua news agency.

The animals began a migration in May     1     their usual habitat in Xishuangbanna,     2     region known for its tropical forest, to the north of the province without clear reason. The herd managed     3     (cross) the Yuanjiang River Sunday, the main obstacle they had to continue their return to a more favorable habitat. The     4     (arrive) of the rainy season in the area in July added difficulty to     5     (it) crossing, since the river flow has increased     6     (considerable). According to Xinhua, authorities blocked the river bank with dozens of trucks to prevent the elephants from crossing,     7    (force) them to continue their journey to a bridge, through     8     they could cross the river without complications. Chen Mingyong, an elephant researcher at Yunnan University, said the Yuanjiang River is the dividing line that marks “the suitability of the environment for the life of elephants”. In the north, the original direction the animals took, it is colder and there is less food,     9     the Yuanjiang River basin, where they are found, has plenty of food.

According to Chen, elephant habitats     10     (divide) into four categories: “highly appropriate, appropriate, normal and inappropriate,” and the animals are now in a suitable one.

A desert doesn’t sound like the most promising place to plant a tree. Yet, since 1978, China     1    (plant)at least 66 billion of them across its desert northern territories, hoping to transform its sandy dry land and yellow dunes     2     a Great Green Wall.

Ian Teh     3    (record)this amazing undertaking while traveling through northern China last year. His expansive photographs show workers tending young trees, blasting them with water and     4    (fill)irrigation tanks. “    5     planting trees sounds great on paper, you can feel doubtful,” Teh says. “When seeing in person, it was impressive.”

The tree-planting strategy is a massive attempt to help fight desertification.     6     (rough) a million square miles of China—a quarter of the country—    7    (cover)in sand. Drought, deforestation, overgrazing and other     8    (problem)threaten an additional 115,000 square miles, fueling very cruel and     9    (violence)sandstorms that regularly blast cities like Beijing and Dunhuang. Many scientists are feeling doubt that planting trees will make a difference in     10     long run. But China’s State Forestry Administration claims the measure has reduced sandstorms by 20 percent and desertification by nearly 5,000 miles in recent years.

Recycling plays a major role     1     fighting against pollution. By recycling paper, we not only save our trees, but we also recycle glass bottles, milk cartons and plastics. It is known to all     2     recycling preserves many nonrenewable resources and reduces green-house gas emissions. Now cleaners send     3     (little) household waste to landfill sites than before and less energy is required when we are making new materials from old ones. Health regulations once prevented recycled plastics from     4     (make) use of to make food containers but new technology has seen this ban lifted in some countries. Rain water     5     (collect) from roads and roofs of buildings is also recycled. Water treatment plants treat     6     (million) of liters a day, removing bacteria and something unwanted. The recycled water cannot be drunk    7     can be used to wash cars, water trees and fight fires, etc. This     8     (mean) there is a reduced demand on drinking water supplies. New technology is     9     (constant) improving recycling techniques in Europe, America and Japan, but countries with small populations may find that these new techniques are so expensive that they cannot     10     (put) into use in the immediate future.