Here is a question about this article: On January 27, 1967, the same day the US and USSR signed the Outer Space Treaty, the crew of the first manned Apollo mission, Command Pilot Virgil "Gus" Grissom, Senior Pilot Edward H. White, and Pilot Roger Chaffee, were killed in a fire that swept through their spacecraft cabin during a ground test, less than a month before the planned February 21 launch. An investigative board determined the fire was probably caused by an electrical spark, and quickly grew out of control, fed by the spacecraft's pure oxygen atmosphere. Crew escape was made impossible by inability to open the plug door hatch cover against the greater-than-atmospheric internal pressure. The board also found design and construction flaws in the spacecraft, and procedural failings, including failure to appreciate the hazard of the pure-oxygen atmosphere, as well as inadequate safety procedures. All these flaws had to be corrected over the next twenty-two months until the first piloted flight could be made. Mercury and Gemini veteran Grissom had been a favored choice of Deke Slayton, NASA's Director of Flight Crew Operations, to make the first piloted landing.
What is the answer to this question: What was the cause of the fire that killed everyone on the first Apollo mission before launch?
****
So... electrical spark

Here is a question about this article: Palermo is Sicily's cultural, economic and touristic capital. It is a city rich in history, culture, art, music and food. Numerous tourists are attracted to the city for its good Mediterranean weather, its renowned gastronomy and restaurants, its Romanesque, Gothic and Baroque churches, palaces and buildings, and its nightlife and music. Palermo is the main Sicilian industrial and commercial center: the main industrial sectors include tourism, services, commerce and agriculture. Palermo currently has an international airport, and a significant underground economy.[citation needed] In fact, for cultural, artistic and economic reasons, Palermo was one of the largest cities in the Mediterranean and is now among the top tourist destinations in both Italy and Europe. The city is also going through careful redevelopment, preparing to become one of the major cities of the Euro-Mediterranean area.
What is the answer to this question: What are Palermo's four main industrial sectors?
****
So... tourism, services, commerce and agriculture

Here is a question about this article: The capital city of Windhoek plays a very important role in Namibia's tourism due to its central location and close proximity to Hosea Kutako International Airport. According to The Namibia Tourism Exit Survey, which was produced by the Millennium Challenge Corporation for the Namibian Directorate of Tourism, 56% of all tourists visiting Namibia during the time period, 2012 - 2013, visited Windhoek. Many of Namibia's tourism related parastatals and governing bodies such as Namibia Wildlife Resorts, Air Namibia and the Namibia Tourism Board as well as Namibia's tourism related trade associations such as the Hospitality Association of Namibia are also all headquartered in Windhoek. There are also a number of notable hotels in Windhoek such as Windhoek Country Club Resort and some international hotel chains also operate in Windhoek, such as Avani Hotels and Resorts and Hilton Hotels and Resorts.
What is the answer to this question: What is the airport in Namibia?
****
So...
Hosea Kutako International Airport