The BeiDou Navigation Satellite System（BDS）is a Chinese satellite navigation system. It consists of two separate satellite constellations（星座）. The first BeiDou system, officially called the BeiDou Satellite Navigation Experimental System and also known as BeiDou-1, consists of three satellites, which since 2000 has offered limited coverage and navigation services, mainly for users in China and neighboring regions. Beidou-1 was decommissioned at the end of 2012.
The second generation of the system, known as COMPASS or BeiDou-2, became operational in China in December 2011 with a partial constellation of 10 satellites in orbit. Since December 2012, it has been offering services to customers in the Asia-Pacific region.
In 2015, China started the build-up of the third generation BeiDou system（BeiDou-3）in the global coverage constellation. The first BDS-3 satellite was launched on 30 March 2015. Up to January 2018, nine BeiDou-3 satellites have been launched. BeiDou-3 will eventually consist of 35 satellites and is expected to provide global services upon completion in 2020. So far, China has sent 27 BeiDou satellites into space. When fully completed, BeiDou, the world's fourth navigation satellite system, following GPS in the United States, GLONASS in Russia and Galileo in the European Union, will provide an alternative global navigation satellite system to the United States owned Global Positioning System（GPS）, and is expected to be more accurate than the GPS. It was claimed in 2016 that BeiDou-3 will reach millimeter-level accuracy（with post-processing）, which is ten times more accurate than the finest level of GPS.
According to China Daily, in 2015, fifteen years after the satellite system was launched, it was generating a turnover of $31.5 billion annually for major companies such as China Aerospace Science and Industry Corp, AutoNavi Holdings Ltd, and China North Industries Group Corp.
A world-wide study of English language proficiency（熟练程度） was carried out in 60 nations. It found that the ability of the French to master the language of English is actually dropping. And that is probably because the French fear to lose their culture. While most countries in the world are slowly improving their English proficiency skills, France is one of the few nations where the English level is actually falling.
France ranked 35th out of sixty countries where English is not the main language, behind China and Italy, and just ahead of the United Arab Emirates（阿拉伯联合酋长国） in the "low proficiency" group. But in all the European countries studied, surprisingly it ranked last, falling behind Germany (14th) and Spain (23rd). Perhaps as is expected, Sweden is on the top, ahead of Norway and the Netherlands. "It means that most of Europe has improved English proficiency," the study said.
The main problem lies with France's fear of losing its own culture and language. The thinking of trying to protect its own culture has a poor influence, and harms the chances of French people learning English. Another factor is about the French school system. "French schools are short of the resources compared to European neighbors. Young pupils learn English in primary school, but often the teachers' level of English is not high. They are qualified as primary teachers, not language teachers, so often their English is just basic." Meanwhile, some also think it is mostly because the French don't care about English at all. They even have a poor attitude towards the English language. The French, more than people of most other nations, take great pride in their language, so in their mind there is no need for them to improve their English.
Even as self-driving cars become more and more popular, there's one problem that Silicon Valley hasn't solved: the traffic jam. But Airbus Group, a U. S. aeronautics and space company, thinks that it has a solution. The company's Silicon Valley branch recently announced it's been working on a secret project titled "Vahana"，an autonomous flying vehicle that can be used for both passenger and cargo (货物) transport.
Airbus' flying taxi resembles a drone in design, and would use multiple propellers (螺旋桨) to travel medium-length distances. Developers in France and Germany are working on an electrically operated platform that would allow the flying taxi to carry multiple passengers once between city destinations. Currently, no countries allow completely autonomous aerial vehicles, so the vehicle would initially be manned by a pilot.
Flight tests of the first Vahana prototype (原型) are planned, in the hope of bringing the product to consumers quickly. That's about a decade sooner than another future-travel system Hyperloop One. "I'm no big fan of Star Wars, but it's not crazy to imagine that one day our big cities will have flying cars making their way along roads in the sky," says Airbus Group CEO Tom Enders. "In a not too distant future, we'll use our smartphones to book a fully automated flying taxi that will land outside our front door - without any pilot."
But before you get too excited about beating rush-hour traffic, it's worth noting that the company has a lot of technological kinks to work out before the product is ready to test. The same sensor technology that allows self-driving cars to avoid accidents doesn't exist for aerial vehicles. Airbus Group isn't the only company trying to get in the autonomous air transportation game. There are a number of cargo drone companies on the market and the Ehang 184, a Chinese passenger drone, began flight testing in June.
Antarctica (南极洲) is the coldest, windiest, highest and driest continent (大陆) on the planet. The lowest temperature ever recorded on Earth was -94.7℃ in eastern Antarctica in 2010. The continent experiences regular Katabatic winds, reaching 300 km per hour. There is little rainfall and the air is very dry. Indeed, the Polar Plateau (极地高原) is regarded as a desert which experiences similar rainfall levels to the Sahara Desert.
It is the fifth-largest continent and is almost 1.5 times the size of the United States. Its coastline covers about 18,000 km. About 98% of the continent is covered in a thick continental ice sheet and the remaining 2% is rock.
Antarctica has six months of daylight followed by six months of darkness. It contains 70% of the planet's freshwater and 90% of the world's ice.
Strong winds and wild storms have been closely connected with Antarctica since its discovery and continue to be a main challenge for modern explorers. Most of the early diaries and tales of exploration of Antarctica are filled with stories of how the weather was man's biggest enemy on the continent. Nature's power is seldom seen as ferocious as it is in Antarctica, making it one of the most difficult places to live on Earth.
The first people to reach the South Pole were from the Norwegian-led expedition (探险队) of Roald Amundsen on December 14, 1911. One month later, Robert Scott's British expedition also reached 90 South but all members unluckily died on their return journey.
Before this, the thought over the existence of a "southern land" was not confirmed until the early 1820s. At this time, British and American business operators and British and Russian national expeditions began exploring the Antarctic Peninsula area and other areas south of the Antarctic Circle. In 1840, it was believed that Antarctica is indeed a continent and not just a group of islands.
