A rising population is one of the main reasons that there is global warming. Between 1650 and 1850 the population increased by 0.75 billion people going from 0.25 billion to one billion. From 1930 to the end of the century the population rose from two billion to over six billion. In just a third of the time the population rose by more than five times what it did before. It is expected that this trend in the changing population will continue and could even heighten. The growing population requires increasing amounts of energy. These energy demands and other supplies require production, which almost always involves the emission of greenhouse gases. The more the population increases the more greenhouse gases that are produced and the greater the increase in temperature.

    The burning of fossil fuels is one of the best-known causes for global warming. The major reason for fossil fuels contributing so much to global warming is the release of carbon that occurs during the burning of fossil fuels. When people burn fossil fuels, they release large amounts of carbon by way of the release of carbon dioxide. The carbon dioxide in the air then leads to global warming.

    Another source of carbon dioxide comes from deforestation. In forests there is a large amount of carbon that is stored in the trees and other plants. This carbon is out of the atmosphere because the trees consume the carbon from carbon dioxide. When people cut down trees, they are frequently burned. This burning releases the carbon dioxide into the atmosphere that was stored in organic matter. Even when new trees are planted, it can take up to one hundred years to make up for the carbon that was released. It is commonly thought that because trees absorb more carbon dioxide, the atmosphere experiences positive effects.

    Sophie Armstrong, the writer of Earth Care put it, “There's no doubt that the earth is becoming warmer because of human activity rather than a random but natural phenomenon.

    How the Grand Canyon (大峡谷) was created remains one of the geology's greatest mysteries. Some evidence suggests that the process was a gradual one in which the Colorado River (which runs through the canyon) slowly cut deeper and deeper into the ground over millions of years. But volcanic rock samples taken from the canyon now suggest that the canyon was down-cut instead.

    Down-cutting is when a flood of water rushes over a landscape (地形) with enough force to cut deeply into the ground and leaves behind a canyon. Such a flood is usually released when a natural or man-made dam (堤坝) bursts.

    Robert Webb, a research geologist, says natural dams seem to have formed and broken across the Colorado River several times during the last million years. The dams were built when lava(熔岩) from the eruptions of nearby volcanoes flowed into the river. The lava hardened into hard rocks and blocked the river, causing it to back up and form a lake. Each time the lake grew so huge that it broke the rock dam, releasing a flash flood that furthered the down-cutting process and deepened the canyon.

    Down-cutting is not just an earthly event. Satellite photos sent back from Mars suggest that the process has happened there, too, say many other researchers.

    The photos, taken by the Mars Global Surveyor, indicate that an enormous lake existed on Mars 3.5 billion years ago. The lake spilled into a large nearby hole. One edge of the hole broke, releasing a flash flood that quickly carved out a grand canyon.

    The existence of down-cutting on Mars is just one more piece of evidence that the cold, dry planet was once warm and wet.

    Luciano Baietti, a retired school headmaster from Italy, holds the Guinness record for the most university degrees. The 70­year­old currently has 15 bachelors(学士) or masters degrees from various universities across Italy, and is getting ready to get his 16th.

    Getting more than one college degree is not exactly unheard­of, but 15 is apparently quite impressive, since it's only been done by one man. Although he spends his days working around his house and garden, like most people his age, at night, Baietti turns into a student again. Every morning, at 3 a. m．， he wakes up and studies by the light of his desk lamp.

    “Thanks to books, I feel free. After all, the words share the same root，” he says, referring to the Italian words libro(book) and libero(free). He is inspired by the 19th century French essayist Louis­Francois Berlin, whose portrait(肖像)is also on display in his study, alongside his many framed university degrees, and whom he describes as “a man of culture and knowledge”．

    Baietti first made it into the Guinness Book of Records in 2002, after his eighth degree. Then he spent the next 15 years adding seven more bachelors and masters degrees to his collection.

    “Each time I set myself a new challenge to see how far my body and my brain can go.” At 70 years old, Baietti thinks he has enough energy for at least one more degree, this time in food science.

    Probably the most important thing about Baietti's achievement is that he managed to get most of his university degrees while working as headmaster of a secondary school, and volunteering with Italy's Red Cross. The secret was always getting up at 3 in the morning to make sure that his thirst for knowledge didn't affect his professional activity and his family life. He spent 3 hours studying every day, and that was apparently all he needed to pass his exams and write his theses (论文)．

    For many years, Bruce Bexler dreamed of going to the lands no human had explored and discovered rare, unknown species. That might sound like an impossible dream, but Bexler turned it into a reality.

    In December 2015, he, together with a team of Australian and American scientists, adventured into a rain forest on the island of New Guinea. They were the first people ever to enter the region. “As we were dropped on the ground by helicopter, we found no trails anywhere; it was really hard to get around,” Bexler says.

    Within minutes of landing, the team spotted a black chicken-like bird. The scientists soon determined that the creature was a type of honeyeater-the first new bird species to be sighted on New Guinea in 60 years. The honeyeater wasn't the only surprise for them. They discovered more than 40 previously unknown plant and animal species. “We were like kids in a candy store?' Bexler recalls. “Everywhere we looked, we saw amazing things we had never seen before.”

    The new found species didn't shy away from the scientists. Two long-nosed echidnas even let the visitors pick them up and take them back to camp to study them. Bexler thinks the animals weren't scared because they had never seen humans before. He explains, “This area gives scientists a place where they can study the behaviours of animals that have not yet learned to be afraid of people.”

    Bexler and his team did not have enough time to study the area completely. “We just scratched the surface, Bexler says. “Anyone who goes there will come back with a mystery.”

    No. 1 Snapchat

    With this app, the pictures people share with friends will disappear automatically(自动地) after they are seen. Snapchat has become more and more popular since 2012. Over 700 million photos have been shown daily by May 2014, up from 20 million per day in 2012.

    No. 2 Uber

    The on-demand car service app allows users to order a ride and get picked up within minutes. On-demand service means no need to reserve (预订) and no waiting in taxi queues. And the app can be used in more than 40 countries.

    No. 3 WhatsApp

    WhatsApp became the world's most popular chat app in 2014 with over 600 million monthly users in August. It was also bought by Facebook in October for about $ 22 billion (about 136 billion yuan).

    No. 4 Venmo

    The mobile payment service is used to share bills by friends, who get together to have dinner or do something else. It took Millennials' (生于1984-1995年间的"千禧一代") smart-phones by storm in 2014. It is said that among college students the word "Venmo" is now being used as a verb—"just Venmo me".

    Sales of Apple's new iPhone 11 in China began on Friday, but were met with a cooler reception from consumers than in previous years. Unlike in previous years, no long lines were seen outside Chinese shops on Friday for the new iPhone, and the product release only made the headlines in a few media outlets.

    Huawei unveiled(公布)its Mate 30 smartphone series on Thursday night. Its new devices have won consumers' hearts at home and abroad. Many compared it with Apple's new iPhone 11, saying that beats the new iPhone in terms of innovation and quality. One customer surnamed Zhao, an IT specialist who pre-ordered a Mate 30 Pro on Friday, said that he chose Mate 30 without hesitation. Zhao said, "It's obvious that Huawei's new phone with its advanced 5G mode would lead the future global telecommunication market, and its new innovative features in gesture and side control attracted my attention, too."

    In contrast with iPhone 11's lukewarm(冷淡的)sales, Chinese netizens have engaged in discussions on Mate 30 and Mate 30 Pro. An online poll on the Mate 30 and iPhone 11 on Weibo on Friday showed that more than 60 percent of netizens chose the Mate 30, while less than 20 percent chose the iPhone 11. Many chose Huawei not out of patriotism (爱国主义)but for its technology.

    Overseas consumers also engaged in active discussions on Huawei's new flagship devices on technology sites and social media platforms. On Twitter, many netizens said "nice", "best phone ever" and "my favorite one" on Huawei's Twitter account. Some netizens in countries like the UK, the Netherlands and Argentina asked when Huawei's new devices would be released in their countries.