Problem: Seven Years%27 War:

Later that summer, the Russians invaded Memel with 75,000 troops. Memel had one of the strongest fortresses in Prussia. However, after five days of artillery bombardment the Russian army was able to storm it. The Russians then used Memel as a base to invade East Prussia and defeated a smaller Prussian force in the fiercely contested Battle of Gross-Jagersdorf on 30 August 1757. However, it was not yet able to take Konigsberg and retreated soon afterward. Still, it was a new threat to Prussia. Not only was Frederick forced to break off his invasion of Bohemia, he was now forced to withdraw further into Prussian-controlled territory. His defeats on the battlefield brought still more opportunist nations into the war. Sweden declared war on Prussia and invaded Pomerania with 17,000 men. Sweden felt this small army was all that was needed to occupy Pomerania and felt the Swedish army would not need to engage with the Prussians because the Prussians were occupied on so many other fronts.

What led to the defeat of the Prussians at Memel?
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A: five days of artillery bombardment

Problem: The most familiar, and historically the oldest, types of glass are "silicate glasses" based on the chemical compound silica (silicon dioxide, or quartz), the primary constituent of sand. The term glass, in popular usage, is often used to refer only to this type of material, which is familiar from use as window glass and in glass bottles. Of the many silica-based glasses that exist, ordinary glazing and container glass is formed from a specific type called soda-lime glass, composed of approximately 75% silicon dioxide (SiO2), sodium oxide (Na2O) from sodium carbonate (Na2CO3), calcium oxide, also called lime (CaO), and several minor additives. A very clear and durable quartz glass can be made from pure silica, but the high melting point and very narrow glass transition of quartz make glassblowing and hot working difficult. In glasses like soda lime, the compounds added to quartz are used to lower the melting temperature and improve workability, at a cost in the toughness, thermal stability, and optical transmittance.
What is sand mostly made of?
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Answer: silica

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Eritrea's ethnic groups each have their own styles of music and accompanying dances. Amongst the Tigrinya, the best known traditional musical genre is the guaila. Traditional instruments of Eritrean folk music include the stringed krar, kebero, begena, masenqo and the wata (a distant/rudimentary cousin of the violin). The most popular Eritrean artist is the Tigrinya singer Helen Meles, who is noted for her powerful voice and wide singing range. Other prominent local musicians include the Kunama singer Dehab Faytinga, Ruth Abraha, Bereket Mengisteab, Yemane Baria, and the late Abraham Afewerki.
What is the best know musical genre amongst the Tigrinya?
A: guaila

Context and question: Marien Ngouabi, who had participated in the coup, assumed the presidency on December 31, 1968. One year later, President Ngouabi proclaimed Congo Africa's first "people's republic", the People's Republic of the Congo, and announced the decision of the National Revolutionary Movement to change its name to the Congolese Labour Party (PCT). Ngouabi survived an attempted coup in 1972 but was assassinated on March 16, 1977. An 11-member Military Committee of the Party (CMP) was then named to head an interim government with Joachim Yhombi-Opango to serve as President of the Republic. Two years later, Yhombi-Opango was forced from power and Denis Sassou Nguesso become the new president.
When did Denis Sassou Nguesso survive a coup?
Answer: unanswerable

Question: In 2008 renewable energy accounted for 8% of the country's total energy consumption, a rise from the 7.2% it accounted for in 2006, but still below the EU average of 10% in 2008. 10% of the country's renewable energy comes from solar power, while most comes from biomass and waste recycling. In line with the European Commission's Directive on Renewable Energy, Greece aims to get 18% of its energy from renewable sources by 2020. In 2013 and for several months, Greece produced more than 20% of its electricity from renewable energy sources and hydroelectric power plants. Greece currently does not have any nuclear power plants in operation, however in 2009 the Academy of Athens suggested that research in the possibility of Greek nuclear power plants begin.
Is there an answer to this question: What was EU average amount of energy from renewable sources in 2008?

Answer: 10%

Problem: Molotov%E2%80%93Ribbentrop Pact:

The treaty was published in the United States for the first time by the St. Louis Post-Dispatch on May 22, 1946, in Britain by the Manchester Guardian. It was also part of an official State Department publication, NaziSoviet Relations 19391941, edited by Raymond J. Sontag and James S. Beddie in January 1948. The decision to publish the key documents on GermanSoviet relations, including the treaty and protocol, had been taken already in spring 1947. Sontag and Beddie prepared the collection throughout the summer of 1947. In November 1947, President Truman personally approved the publication but it was held back in view of the Foreign Ministers Conference in London scheduled for December. Since negotiations at that conference did not prove constructive from an American point of view, the document edition was sent to press. The documents made headlines worldwide. State Department officials counted it as a success: "The Soviet Government was caught flat-footed in what was the first effective blow from our side in a clear-cut propaganda war."

Which world leader favored the publication of Nazi-Soviet Relations to be printed?
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A:
President Truman