Problem: Mandolin:

Beginning with the Paris Exposition of 1878, the instrument's popularity rebounded. The Exposition was one of many stops for a popular new performing group the Estudiantes Espanoles (Spanish Students). They danced and played guitars, violins and the bandurria, which became confused with the mandolin. Along with the energy and awareness created by the day's hit sensation, a wave of Italian mandolinists travelled Europe in the 1880s and 1890s and in the United States by the mid-1880s, playing and teaching their instrument. The instrument's popularity continued to increase during the 1890s and mandolin popularity was at its height in "early years of the 20th century." Thousands were taking up the instrument as a pastime, and it became an instrument of society, taken up by young men and women. Mandolin orchestras were formed worldwide, incorporating not only the mandolin family of instruments, but also guitars, double basses and zithers.

What instrument did the violin become confused with?
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A: unanswerable

Problem: While Goring was optimistic the Luftwaffe could prevail, Hitler was not. On 17 September he postponed Operation Sea Lion (as it turned out, indefinitely) rather than gamble Germany's newly gained military prestige on a risky cross-Channel operation, particularly in the face of a sceptical Joseph Stalin in the Soviet Union. In the last days of the battle, the bombers became lures in an attempt to draw the RAF into combat with German fighters. But their operations were to no avail; the worsening weather and unsustainable attrition in daylight gave the OKL an excuse to switch to night attacks on 7 October.
When did the OKL switch to night raids?
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Answer: 7 October

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Ongoing political tensions between Great Britain and the thirteen colonies reached a crisis in 1774 when the British placed the province of Massachusetts under martial law after the Patriots protested taxes they regarded as a violation of their constitutional rights as Englishmen. When shooting began at Lexington and Concord in April 1775, militia units from across New England rushed to Boston and bottled up the British in the city. The Continental Congress appointed George Washington as commander-in-chief of the newly created Continental Army, which was augmented throughout the war by colonial militia. He drove the British out of Boston but in late summer 1776 they returned to New York and nearly captured Washington's army. Meanwhile, the revolutionaries expelled British officials from the 13 states, and declared themselves an independent nation on July 4, 1776.
When did the colonies declare independence?
A: July 4, 1776

Context and question: A new index was released on December 18, 2008. This so-called "statistical update" covered the period up to 2006 and was published without an accompanying Human Development Report. The update is relevant due to newly released estimates of purchasing power parities (PPP), implying substantial adjustments for many countries, resulting in changes in HDI values and, in many cases, HDI ranks.
What was the index published on December 18, 2008 complete?
Answer: unanswerable

Question: As the number of possible tests for even simple software components is practically infinite, all software testing uses some strategy to select tests that are feasible for the available time and resources. As a result, software testing typically (but not exclusively) attempts to execute a program or application with the intent of finding software bugs (errors or other defects). The job of testing is an iterative process as when one bug is fixed, it can illuminate other, deeper bugs, or can even create new ones.
Is there an answer to this question: software testing attempts to eliminate a program for what reason?

Answer: unanswerable

Question: Classical statistical mechanics requires the existence of h (but does not define its value). Eventually, following upon Planck's discovery, it was recognized that physical action cannot take on an arbitrary value. Instead, it must be some multiple of a very small quantity, the "quantum of action", now called the Planck constant. Classical physics cannot explain this fact. In many cases, such as for monochromatic light or for atoms, this quantum of action also implies that only certain energy levels are allowed, and values in between are forbidden.
Is there an answer to this question: What is not required to exist in modern statistics mechanics?

Answer:
unanswerable