The problem: Answer a question about this article:
A major turning point in the development of DC machines took place in 1864, when Antonio Pacinotti described for the first time the ring armature with its symmetrically grouped coils closed upon themselves and connected to the bars of a commutator, the brushes of which delivered practically non-fluctuating current. The first commercially successful DC motors followed the invention by Zénobe Gramme who, in 1871, reinvented Pacinotti's design. In 1873, Gramme showed that his dynamo could be used as a motor, which he demonstrated to great effect at exhibitions in Vienna and Philadelphia by connecting two such DC motors at a distance of up to 2 km away from each other, one as a generator. (See also 1873 : l'expérience décisive [Decisive Workaround] .)
In what two cities did Gramme conduct his demonstrations?
****
The answer: Vienna and Philadelphia


The problem: Answer a question about this article:
Chopin took the new salon genre of the nocturne, invented by the Irish composer John Field, to a deeper level of sophistication. He was the first to write ballades and scherzi as individual concert pieces. He essentially established a new genre with his own set of free-standing preludes (Op. 28, published 1839). He exploited the poetic potential of the concept of the concert étude, already being developed in the 1820s and 1830s by Liszt, Clementi and Moscheles, in his two sets of studies (Op. 10 published in 1833, Op. 25 in 1837).
Chopin was the first person to create what as singular concert pieces?
****
The answer: ballades and scherzi


The problem: Answer a question about this article:
The Soviets also helped Germany to avoid British naval blockades by providing a submarine base, Basis Nord, in the northern Soviet Union near Murmansk. This also provided a refueling and maintenance location, and a takeoff point for raids and attacks on shipping. In addition, the Soviets provided Germany with access to the Northern Sea Route for both cargo ships and raiders (though only the commerce raider Komet used the route before the German invasion), which forced Britain to protect sea lanes in both the Atlantic and the Pacific.
What did the Germans use to avoid British blockades?
****
The answer: a submarine base


The problem: Answer a question about this article:
In May and June 1835, the area which is now central and northern Melbourne was explored by John Batman, a leading member of the Port Phillip Association in Van Diemen's Land (now known as Tasmania), who claimed to have negotiated a purchase of 600,000 acres (2,400 km2) with eight Wurundjeri elders. Batman selected a site on the northern bank of the Yarra River, declaring that "this will be the place for a village". Batman then returned to Launceston in Tasmania. In early August 1835 a different group of settlers, including John Pascoe Fawkner, left Launceston on the ship Enterprize. Fawkner was forced to disembark at Georgetown, Tasmania, because of outstanding debts. The remainder of the party continued and arrived at the mouth of the Yarra River on 15 August 1835. On 30 August 1835 the party disembarked and established a settlement at the site of the current Melbourne Immigration Museum. Batman and his group arrived on 2 September 1835 and the two groups ultimately agreed to share the settlement.
Current central and northern Melbourne was explored by whom?
****
The answer:
John Batman