Problem: Josip Broz Tito:

On 6 April 1941, German forces, with Hungarian and Italian assistance, launched an invasion of Yugoslavia. On 10 April 1941, Slavko Kvaternik proclaimed the Independent State of Croatia, and Tito responded by forming a Military Committee within the Central Committee of the Yugoslav Communist Party. Attacked from all sides, the armed forces of the Kingdom of Yugoslavia quickly crumbled. On 17 April 1941, after King Peter II and other members of the government fled the country, the remaining representatives of the government and military met with the German officials in Belgrade. They quickly agreed to end military resistance. On 1 May 1941, Tito issued a pamphlet calling on the people to unite in a battle against the occupation. On 27 June 1941, the Central Committee of the Communist Party of Yugoslavia appointed Tito Commander in Chief of all project national liberation military forces. On 1 July 1941, the Comintern sent precise instructions calling for immediate action.

When did German forces launch an invasion of Yugoslavia?
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A: 6 April 1941

Problem: New York is also a major center for non-commercial educational media. The oldest public-access television channel in the United States is the Manhattan Neighborhood Network, founded in 1971. WNET is the city's major public television station and a primary source of national Public Broadcasting Service (PBS) television programming. WNYC, a public radio station owned by the city until 1997, has the largest public radio audience in the United States.
What is the name of the first public-access TV channel in the country?
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Answer: Manhattan Neighborhood Network

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The French breech-loading rifle, the Chassepot, had a far longer range than the German needle gun; 1,500 yards (1,400 m) compared to 600 yd (550 m). The French also had an early machine-gun type weapon, the mitrailleuse, which could fire its thirty-seven barrels at a range of around 1,200 yd (1,100 m). It was developed in such secrecy, that little training with the weapon had occurred, leaving French gunners with no experience; the gun was treated like artillery and in this role it was ineffective. Worse still, once the small number of soldiers who had been trained how to use the new weapon became casualties, there were no replacements who knew how to operate the mitrailleuse.
Treating the mitrailleuse like what rendered it far less effective
A: artillery

Context and question: Many older buildings in certain areas of Boston are supported by wooden piles driven into the area's fill; these piles remain sound if submerged in water, but are subject to dry rot if exposed to air for long periods. Groundwater levels have been dropping, to varying degrees, in many areas of the city, due in part to an increase in the amount of rainwater discharged directly into sewers rather than absorbed by the ground. A city agency, the Boston Groundwater Trust, coordinates monitoring of groundwater levels throughout the city via a network of public and private monitoring wells. However, Boston's drinking water supply, from the Quabbin and Wachusett Reservoirs to the west, is one of the very few in the country so pure as to satisfy federal water quality standards without filtration.
The piles begin to rot if exposed to what?
Answer: air

Question: Consequently, Molotov, fearing that EDC would be directed in the future against the USSR therefore "seeking to prevent the formation of groups of European States directed against other European States", made a proposal for a General European Treaty on Collective Security in Europe "open to all European States without regard as to their social systems" which would have included the unified Germany (thus making the EDC perceived by the USSR as a threat unusable). But Eden, Dulles and Bidault opposed the proposal.
Is there an answer to this question: What treaty would make the EDC usable?

Answer: unanswerable

Greenhouses convert solar light to heat, enabling year-round production and the growth (in enclosed environments) of specialty crops and other plants not naturally suited to the local climate. Primitive greenhouses were first used during Roman times to produce cucumbers year-round for the Roman emperor Tiberius. The first modern greenhouses were built in Europe in the 16th century to keep exotic plants brought back from explorations abroad. Greenhouses remain an important part of horticulture today, and plastic transparent materials have also been used to similar effect in polytunnels and row covers.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Where were the first modern greenhouses built?
Ah, so..
Europe