Problem: Mandolin:

Though almost any variety of acoustic mandolin might be adequate for Irish traditional music, virtually all Irish players prefer flat-backed instruments with oval sound holes to the Italian-style bowl-back mandolins or the carved-top mandolins with f-holes favoured by bluegrass mandolinists. The former are often too soft-toned to hold their own in a session (as well as having a tendency to not stay in place on the player's lap), whilst the latter tend to sound harsh and overbearing to the traditional ear. The f-hole mandolin, however, does come into its own in a traditional session, where its brighter tone cuts through the sonic clutter of a pub. Greatly preferred for formal performance and recording are flat-topped "Irish-style" mandolins (reminiscent of the WWI-era Martin Army-Navy mandolin) and carved (arch) top mandolins with oval soundholes, such as the Gibson A-style of the 1920s.

Which mandolin wasn't preferred for formal performances and recordings?
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A: unanswerable


Problem: Nueva Vizcaya (New Biscay) was the first province of northern New Spain to be explored and settled by the Spanish. Around 1528, a group of Spaniard explorers, led by Álvar Núñez Cabeza de Vaca, first entered the actual territory of what is now Chihuahua. The conquest of the territory lasted nearly one century, and encountered fierce resistance from the Conchos tribe, but the desire of the Spanish Crown to transform the region into a bustling mining center led to a strong strategy to control the area.
The Spanish crown wanted to turn the region into what type of industry?
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Answer: mining center


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Insects are the only invertebrates to have developed active flight capability, and this has played an important role in their success.:186 Their muscles are able to contract multiple times for each single nerve impulse, allowing the wings to beat faster than would ordinarily be possible. Having their muscles attached to their exoskeletons is more efficient and allows more muscle connections; crustaceans also use the same method, though all spiders use hydraulic pressure to extend their legs, a system inherited from their pre-arthropod ancestors. Unlike insects, though, most aquatic crustaceans are biomineralized with calcium carbonate extracted from the water.
Insects have developed what kind of active capability?
A: flight


Context and question: While the Ming dynasty traded horses with Tibet, it upheld a policy of outlawing border markets in the north, which Laird sees as an effort to punish the Mongols for their raids and to "drive them from the frontiers of China." However, after Altan Khan (1507–1582)—leader of the Tümed Mongols who overthrew the Oirat Mongol confederation's hegemony over the steppes—made peace with the Ming dynasty in 1571, he persuaded the Ming to reopen their border markets in 1573. This provided the Chinese with a new supply of horses that the Mongols had in excess; it was also a relief to the Ming, since they were unable to stop the Mongols from periodic raiding. Laird says that despite the fact that later Mongols believed Altan forced the Ming to view him as an equal, Chinese historians argue that he was simply a loyal Chinese citizen. By 1578, Altan Khan formed a formidable Mongol-Tibetan alliance with the Gelug that the Ming viewed from afar without intervention.
Who did the Ming trade horses with?
Answer: Tibet


Question: The city hockey club, Southampton Hockey Club, founded in 1938, is now one of the largest and highly regarded clubs in Hampshire, fielding 7 senior men's and 5 senior ladies teams on a weekly basis along with boys’ and girls’ teams from 6 upwards.
Is there an answer to this question: Weekly, how many senior ladies teams does Southampton Hockey Club field?

Answer: 5


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
One of the problems of the standard electric light bulb is filament notching due to evaporation of the filament. Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Irving Langmuir found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly argon and some nitrogen, or sometimes krypton. Lamps operated on direct current develop random stairstep irregularities on the filament surface which may cut lifespan in half compared to AC operation; different alloys of tungsten and rhenium can be used to counteract the effect.
Which gases are typically used in a light bulb?
A:
argon and some nitrogen, or sometimes krypton