Problem: Gramophone record:

Vinyl records do not break easily, but the soft material is easily scratched. Vinyl readily acquires a static charge, attracting dust that is difficult to remove completely. Dust and scratches cause audio clicks and pops. In extreme cases, they can cause the needle to skip over a series of grooves, or worse yet, cause the needle to skip backwards, creating a "locked groove" that repeats over and over. This is the origin of the phrase "like a broken record" or "like a scratched record", which is often used to describe a person or thing that continually repeats itself. Locked grooves are not uncommon and were even heard occasionally in radio broadcasts.

What causes clicks and pops on vinyl records?
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A: Dust and scratches

Problem: Group (mathematics):

Mathematicians often strive for a complete classification (or list) of a mathematical notion. In the context of finite groups, this aim leads to difficult mathematics. According to Lagrange's theorem, finite groups of order p, a prime number, are necessarily cyclic (abelian) groups Zp. Groups of order p2 can also be shown to be abelian, a statement which does not generalize to order p3, as the non-abelian group D4 of order 8 = 23 above shows. Computer algebra systems can be used to list small groups, but there is no classification of all finite groups.q["] An intermediate step is the classification of finite simple groups.r["] A nontrivial group is called simple if its only normal subgroups are the trivial group and the group itself.s["] The JordanHolder theorem exhibits finite simple groups as the building blocks for all finite groups. Listing all finite simple groups was a major achievement in contemporary group theory. 1998 Fields Medal winner Richard Borcherds succeeded in proving the monstrous moonshine conjectures, a surprising and deep relation between the largest finite simple sporadic groupthe "monster group"and certain modular functions, a piece of classical complex analysis, and string theory, a theory supposed to unify the description of many physical phenomena.

What is used to classify all finite groups?
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A: unanswerable

Problem: Cork (city):

Cork was originally a monastic settlement, reputedly founded by Saint Finbarr in the 6th century. Cork achieved an urban character at some point between 915 and 922 when Norseman (Viking) settlers founded a trading port. It has been proposed that, like Dublin, Cork was an important trading centre in the global Scandinavian trade network. The ecclesiastical settlement continued alongside the Viking longphort, with the two developing a type of symbiotic relationship; the Norsemen providing otherwise unobtainable trade goods for the monastery, and perhaps also military aid.

What kind of settlement was Cork?
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A: ecclesiastical

Problem: Nanjing:

Nanjing's airport, Lukou International Airport, serves both national and international flights. In 2013, Nanjing airport handled 15,011,792 passengers and 255,788.6 tonnes of freight. The airport currently has 85 routes to national and international destinations, which include Japan, Korea, Thailand, Malaysia, Singapore, USA and Germany. The airport is connected by a 29-kilometre (18 mi) highway directly to the city center, and is also linked to various intercity highways, making it accessible to the passengers from the surrounding cities. A railway Ninggao Intercity Line is being built to link the airport with Nanjing South Railway Station. Lukou Airport was opened on 28 June 1997, replacing Nanjing Dajiaochang Airport as the main airport serving Nanjing. Dajiaochang Airport is still used as a military air base.

What airport was the primary airport before Lukou?
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A:
Nanjing Dajiaochang Airport