2 . Endangered polar bears are breeding (繁殖) with grizzly bears (灰熊), creating “pizzaly” bears (灰北极熊), which is being driven by climate change, scientists say.

As the world warms and Arctic sea ice thins, starving (饥饿的) polar bears are being forced ever further south to relieve (减轻) hunger, where they meet grizzlies, whose ranges (范围) are expanding northwards. And with that growing contact between the two come increasing hybrids (杂交种).

With characteristics that could give the hybrids an advantage in warming northern habitats, some scientists guess that they could be here to stay. “Usually, hybrids aren’t better suited to their environments than their parents, but these hybrids are able to search for a broader range of food sources,” Larisa DeSantis, an associate professor of biological sciences at Vanderbilt University, told Live Science.

The rise of “pizzly” bears appears with polar bears’ decline: their numbers are estimated to decrease (减少) by more than 30% in the next 30 years. This sudden fall is linked partly to “pizzly” bears taking up polar bears’ ranges, where they outcompete (超越) them, but also to polar bears’ highly specialized diets.

“Polar bears mainly consumed (消耗) soft foods even during the Medieval Warm Period, a previous period of rapid warming,” DeSantis said, referring to fat meals such as seals. “Although all of these starving polar bears are trying to find alternative (可替代的) food sources, like seabird eggs, it could be a tipping point fo r their survival.” Actually, the calories they gain from these sources do not balance out those they burn from searching for them. This could result in a habitat ready for the hybrids to move in and take over, leading to a loss in biodiversity (生物多样性) if polar bears are replaced.

“We’re having massive impacts with climate change on species,” DeSantis said. “The polar bear is telling us how bad things are. In some sense, ‘pizzaly’ bears could be a sad but necessary. compromise given current warming trends.”

3 . Life today is much easier than it was hundreds of years ago, but has brought new peoplems. One of the biggest is pollution. Pollution come in many ways. We see it, smell it, drink it and even hear it.

Men have been polluting the earth. Many years ago, the pollution was not so serious because there were not so many people. When the land was used up or the river was dirty in one place, men moved to another place.

Air pollution is now the most serious. Air makes people sick. And lots of people now are trying to use something to clear the air. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us become angry more easily.

Many countries are making rules to fight air pollution. They stop people from burning coal in houses and factories in the city, and from putting dirty smoke into the air.

Pollution by SO² is now the most dangerous kind of air pollution. It is caused by heavy traffic. It is true that if there are fewer people driving, there will be less air pollution.

Although most of the pollution is caused by us, we are the ones who can change the situation. The earth is our home. We must take care of it. And we must pay more attention to the information in pollution at the same time.

Tibetan antelopes live on the plains of Tibet, Xinjiang and Qinghai. When I     1     (watch) them move slowly across the green grass, I am struck by their     2     (beautiful). At the same time, I am also reminded     3     the danger they are in. Right now they     4     (hunt), illegally, for their valuable fur.

Zhaxi who works at the Nature Reserve (保护区) says, “    5     (actual), we are trying to save ourselves, not only the animals.” In the 1980-1990, the number of the antelopes     6     (reduce) by 50 percent. The hunters were shooting antelopes     7     (make) profits. Their habitats were becoming     8     (small) than before,     9     new roads and railways were built.

In order to save them, the government take     10     (effect) measures and the antelope population has recovered. In June, 2015, the Tibetan antelopes was removed from the endangered list.