Question: An airport is an aerodrome with facilities for flights to take off and land. Airports often have facilities to store and maintain aircraft, and a control tower. An airport consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface such as a runway for a plane to take off or a helipad, and often includes adjacent utility buildings such as control towers, hangars and terminals. Larger airports may have fixed base operator services, airport aprons, air traffic control centres, passenger facilities such as restaurants and lounges, and emergency services.
Is there an answer to this question: What is an aerially accessible open space that includes at least one active surface such as a runway or a helipad?

Answer: landing area

Question: Whitehead and Russell had thought originally that Principia Mathematica would take a year to complete; it ended up taking them ten years. To add insult to injury, when it came time for publication, the three-volume work was so massive (more than 2,000 pages) and its audience so narrow (professional mathematicians) that it was initially published at a loss of 600 pounds, 300 of which was paid by Cambridge University Press, 200 by the Royal Society of London, and 50 apiece by Whitehead and Russell themselves. Despite the initial loss, today there is likely no major academic library in the world which does not hold a copy of Principia Mathematica.
Is there an answer to this question: Who paid to publish Principia Mathematica?

Answer: Cambridge University Press

Question: In May 2014, the Government of China banned the internal purchase of Windows 8-based products under government contracts requiring "energy-efficient" devices. The Xinhua News Agency claimed that Windows 8 was being banned in protest of Microsoft's support lifecycle policy and the end of support for Windows XP (which, as of January 2014, had a market share of 49% in China), as the government "obviously cannot ignore the risks of running OS [sic] without guaranteed technical support." However, Ni Guangnan of the Chinese Academy of Sciences had also previously warned that Windows 8 could allegedly expose users to surveillance by the United States government due to its heavy use of internet-based services.
Is there an answer to this question: What market share did Windows XP have in Chine?

Answer: 49%

Question: AC radio stations may play mainstream music, but they will exclude hip hop, dance tracks, hard rock, and some forms of teen pop, as they are less popular amongst the target demographic of these radio stations, which is intended for an adult audience. AC radio often targets the 2544 age group, the demographic that has received the most attention from advertisers since the 1960s. A common practice in recent years is that many adult contemporary stations play less newer music because they also give ample airtime to hits of the past, so the de-emphasis on new songs slows the progression of the AC chart.
Is there an answer to this question: When did advertisers begin to focus on the adult contemporary age demographic?

Answer:
1960s