The world itself is becoming much smaller by using modern traffic and modern communication means. Life today is much easier than it was hundreds of years ago, but it has brought new problems. One of the biggest is pollution. To pollute means to make things dirty. Pollution comes in many ways. We see it, smell it, drink it and even hear it.

    Man has been polluting the earth. The more people, the more pollution. Many years ago, the problem 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, man moved to another place. But this is no longer true. Man is now slowly polluting the whole world.

    Air pollution is still the most serious. It's bad for all living things in the world, but it is not the only one kind of pollution. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us angry more easily.

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

    Pollution by carbon dioxide 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.

    The earth is our home. We must take care of it. That means keeping the land, water and air clean. And we must take care of the rise in population at the same time.

    Winters are cold in northern British Colunbia, a province of Canada. That's one reason why two girls become concerned about a number of homeless cats in their town.

    "My dad first saw this big cat problem…and he knew the man who had all the cats," says Vivienne Thompson. Vivienne and her friend Catrina Vanderwolf learned that the man wasn't happy about all the cats living around his home. They offered to help.

    Each day after school all winter long, the girls walked two miles to feed the cats. "We could see all their footprints in the snow and at first couldn't understand why they wouldn't let us get close to them," explained the girls.

    They contacted(联系)Valerie Ingram at the Lakes Animal Friendship Society, who told them that the cats are "feral." They belong to no one. Feral cats have little or no contact with humans in their entire lives. The large colony(群) of cats likely started with two stray(流浪的) cats who had a litter of kittens. Those cats had kittens, and before long, there were dozens of homeless cats.

To get the cat colony under control, the cats would need operations so that they could no longer have kittens. Vivienne and Catrina shared what they learned with their teachers and other students—and a project began! Grassy Plains School started raising money to pay for the cats' operations. Before long, local organizations and large companies agreed to help.

    Volunteers spent months humanely trapping the cats. Finally, all the cats had been operated on and returned to the colony.

"We were so happy to be a part of helping, to get to know the cats, to not see suffering anymore, only happy cats—and a happy man who feeds them on his step now," say Vivienne and Catrina.

    The world's first-known nursery for baby giant manta rays(蝠鲼) has been discovered hidden away in the Gulf of Mexico, the place of 70 miles off the coast of Texas, after studying decades of giant manta ray data from the area by the scientists.

    Where the baby manta rays grow up has long troubled scientists, as they are rarely spotted in the four to five years it takes them to become adults, when they can often grow to more than 20ft wide.

In the study Mr Stewart and colleagues describe a reef (暗礁)—filled with mantas of all ages—where the sea floor runs down into deeper water. He said "We think they may be feeding on specific types of zooplankton(浮游生物) there, then migrating up toward the surface, where we saw them. They might be hanging around the banks because it could be a little safer than open water. We've seen them so rarely that we know very little about these baby manta rays. We don't know how far they move, or exactly what they feed on, or all of the habitats these access.”

    Giant manta rays are listed as species dying out by protectors, although actual population numbers of the mysterious "gentle giant" are hard to calculate. Sightings of the closely-related reef manta, however, have dropped by 90 percent in regions of southeast Asia in the past decade, according to a study.

    Fishing is considered the biggest threat to giant manta numbers, both intentional and accidental. Their gill plates(腮下肉)- the parts through which they filter(过滤) their food from seawater-are sold in China for medical purposes, while they often end up as something caught by mistake due to their huge wings.

    When you eat fish, you probably eat it off a plate, using a fork. Well, the dolphins in Shark Bay, Australia, eat their fish from conch（海螺）shells!

    Scientists have found some of these bottlenose dolphins（宽吻海豚）using their large beaks to trap fish in shells underwater. Then, carrying the shells to the surface, they shake out the fish into their mouths and eat them. Clearly, using the conch shells allows the dolphins to catch more fish than they would be able to without such a tool. The technique has been called "conching".

    Researchers noticed dolphins engaging in the behavior a handful of times from 2007 to 2009. This dolphin trend seemed to become popular.

    Simon Allen, a scientist, was surprised to see the conching technique spreading. "In the lasts four months alone, the research team have seen and photographed the behavior no less than six times, possibly even seven," he said in a press release. He thinks the dolphins may be learning conching from one another.

    Dolphins are known to be highly intelligent. The size of their brain is large in proportion（比例）to their body size. Compared with other animals, they have highly developed communication and social skills. This species of dolphin also uses other tools. They will break off pieces of sponges that grow in the ocean, for example, and use them to cover their beaks. This allows them to search for food on the ocean floor without hurting their noses.

    Scientists are going to keep trying to catch the dolphins in the act of conching. They hope to see evidence of the dolphins teaching one another the technique. They also want to know how the dolphins get fish in the conch shell. Do they push the fish into the shell with their beaks? Or do they chase the fish into the shell before carrying them up to eat?

    However they do it, Allen believes these dolphins to be particularly clever. "I wouldn't be too surprised to find such cunning ploys being adopted by Shark Bay's bottlenose dolphins," he said in statement.

    Distance, just like currency, becomes incomprehensible when it reaches large quantities.

    So, when outdoor enthusiast and Midwest Mountaineering employee Elizabeth John says she only hiked the nearly 500 miles of the Colorado Trail over a period of six weeks, don't let her fool you. That's like walking from St. Paul to St. Louis—give or take a few dozen miles—plus thousands upon thousands of feet of altitude.

    "I'm a gardener, I'm a busy-hands person, but busy feet are just as good," she explains. "I don't meditate, but maybe that's the way I think about it—walking as a way to relax."

    John took childhood hikes in the Boundary Waters and caught her case of busy feet while hiking in Alaska as a teenager. With a background in paddling, mountaineering, and backpacking, she found long-distance hiking rewarding, though exhausting.

    Since then, thru-hiking—hiking a long-distance trail (考验，试验) end-to-end in one hiking season—has gotten friendlier to beginners. John has given up 60-pound packs in favor of a lighter modern backpacking equipment. For her 50th birthday, she decided to fly to Spain and walk close to 500 miles of the Camino de Santiago. The Colorado jaunt, her first solo long-distance hike, followed a few years later in 2017.

    "Going on a big walk is unreasonable and includes being uncomfortable, wet, hungry, sore, tired, lonely…it's challenging," she says. "It's a leap of faith. But I found the rewards surprising and unexpected, some even waiting for me at home after the trip. There is a rhythm to walking, a physicality and simplicity…a discovery."

    Logging some 4, 000 feet of elevation daily, John met many "trail angels" who provided shade, snacks, and sometimes beer at remote points in the wilderness, purely out of the goodness of their hearts. "You're so excited, because you're someplace so incredible, and it wasn't easy to get there," she says. "There was this moment when you love humanity, and you're so proud of people for doing it."