Problem: Buckingham Palace:

Formerly, men not wearing military uniform wore knee breeches of an 18th-century design. Women's evening dress included obligatory trains and tiaras or feathers in their hair (or both). The dress code governing formal court uniform and dress has progressively relaxed. After World War I, when Queen Mary wished to follow fashion by raising her skirts a few inches from the ground, she requested a lady-in-waiting to shorten her own skirt first to gauge the king's reaction. King George V was horrified, so the queen kept her hemline unfashionably low. Following their accession in 1936, King George VI and his consort, Queen Elizabeth, allowed the hemline of daytime skirts to rise. Today, there is no official dress code. Most men invited to Buckingham Palace in the daytime choose to wear service uniform or lounge suits; a minority wear morning coats, and in the evening, depending on the formality of the occasion, black tie or white tie.

What century were men's knee breeches forbidden at Buckingham?
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A: unanswerable


Problem: Greece is a developed country with high standards of living[citation needed] and high Human Development Index. Its economy mainly comprises the service sector (85.0%) and industry (12.0%), while agriculture makes up 3.0% of the national economic output. Important Greek industries include tourism (with 14.9 million international tourists in 2009, it is ranked as the 7th most visited country in the European Union and 16th in the world by the United Nations World Tourism Organization) and merchant shipping (at 16.2% of the world's total capacity, the Greek merchant marine is the largest in the world), while the country is also a considerable agricultural producer (including fisheries) within the union.
Greece holds what rank among most visited countries in the world?
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Answer: 16th


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The value of the deposit was obvious from the start, but the means of extracting the bitumen were not. The nearest town, Fort McMurray, Alberta was a small fur trading post, other markets were far away, and transportation costs were too high to ship the raw bituminous sand for paving. In 1915, Sidney Ells of the Federal Mines Branch experimented with separation techniques and used the bitumen to pave 600 feet of road in Edmonton, Alberta. Other roads in Alberta were paved with oil sands, but it was generally not economic. During the 1920s Dr. Karl A. Clark of the Alberta Research Council patented a hot water oil separation process and entrepreneur Robert C. Fitzsimmons built the Bitumount oil separation plant, which between 1925 and 1958 produced up to 300 barrels (50 m3) per day of bitumen using Dr. Clark's method. Most of the bitumen was used for waterproofing roofs, but other uses included fuels, lubrication oils, printers ink, medicines, rust and acid-proof paints, fireproof roofing, street paving, patent leather, and fence post preservatives. Eventually Fitzsimmons ran out of money and the plant was taken over by the Alberta government. Today the Bitumount plant is a Provincial Historic Site.
For what was most of the the Bitumont plant's output was used for waterproofing?
A: roofs


Context and question: Meanwhile, the Industrial Revolution laid open the door for mass production and consumption. Aesthetics became a criterion for the middle class as ornamented products, once within the province of expensive craftsmanship, became cheaper under machine production.
 As products came within their financial reach what concept began to interest the lower class?
Answer: unanswerable


Question: Pomors are distinguished by the presence of Y Haplogroup N among them. Postulated to originate from southeast Asia, it is found at high rates in Uralic peoples. Its presence in Pomors (called "Northern Russians" in the report) attests to the non-Slavic tribes (mixing with Finnic tribes of northern Eurasia). Autosomally, Russians are generally similar to populations in central-eastern Europe but some northern Russians are intermediate to Finno-Ugric groups.
Is there an answer to this question: What are Y Haplogroup N distinguished by?

Answer: unanswerable


Tucson's primary electrical power source is a coal and natural gas power-plant managed by Tucson Electric Power that is situated within the city limits on the south-western boundary of Davis-Monthan Air-force base adjacent to Interstate-10. The air pollution generated has raised some concerns as the Sundt operating station has been online since 1962 as is exempt from many pollution standards and controls due to its age. Solar has been gaining ground in Tucson with its ideal over 300 days of sunshine climate. Federal, state, and even local utility credits and incentives have also enticed residents to equip homes with solar systems. Davis-Monthan AFB has a 3.3 Megawatt (MW) ground-mounted solar photovoltaic (PV) array and a 2.7 MW rooftop-mounted PV array, both of which are located in the Base Housing area. The base will soon have the largest solar-generating capacity in the United States Department of Defense after awarding a contract on September 10, 2010, to SunEdison to construct a 14.5 MW PV field on the northwestern side of the base.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What does Tucson's main power plant use for fuel?
Ah, so..
coal and natural gas