Problem: Aspirated consonant:

Later, during the Koine Greek period, the aspirated and voiceless stops /t d/ of Attic Greek lenited to voiceless and voiced fricatives, yielding / / in Medieval and Modern Greek.

The lenited Attic Greek yielded / / in what periods?
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A: Medieval and Modern Greek

Problem: On March 17, 1991, an all-Russian referendum created the post of President of the RSFSR. On June 12, Boris Yeltsin was elected President of Russia by popular vote. During an unsuccessful coup attempt on August 1921, 1991 in Moscow, the capital of the Soviet Union and Russia, President of Russia Yeltsin strongly supported the President of the Soviet Union, Mikhail Gorbachev.
On what date was the office of President of the RSFSR not created?
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Answer: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In the early 19th century, Augustus Welby Northmore Pugin wrote Contrasts (1836) that, as the titled suggested, contrasted the modern, industrial world, which he disparaged, with an idealized image of neo-medieval world. Gothic architecture, Pugin believed, was the only "true Christian form of architecture."
When did Augustus Welby Northmore Pugin paint the artwork called Contrasts?
A: unanswerable

Context and question: The Napoleonic Wars were the cause of the final dissolution of the Holy Roman Empire, and ultimately the cause for the quest for a German nation state in 19th-century German nationalism. After the Congress of Vienna, Austria and Prussia emerged as two competitors. Austria, trying to remain the dominant power in Central Europe, led the way in the terms of the Congress of Vienna. The Congress of Vienna was essentially conservative, assuring that little would change in Europe and preventing Germany from uniting. These terms came to a sudden halt following the Revolutions of 1848 and the Crimean War in 1856, paving the way for German unification in the 1860s. By the 1820s, large numbers of Jewish German women had intermarried with Christian German men and had converted to Christianity. Jewish German Eduard Lasker was a prominent German nationalist figure who promoted the unification of Germany in the mid-19th century.
When was the Crimean War?
Answer: 1856

Question: In 2009, the Internet Archive migrated its customized storage architecture to Sun Open Storage, and hosts a new data center in a Sun Modular Datacenter on Sun Microsystems' California campus.
Is there an answer to this question: Which campus did Internet Archive adopt 2009?

Answer: unanswerable

Question: Together with caesium and gold (both yellow), and osmium (bluish), copper is one of only four elemental metals with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells the energy difference between these shells is such that it corresponds to orange light. The same mechanism accounts for the yellow color of gold and caesium.
Is there an answer to this question: What color is fake copper?

Answer:
unanswerable