Problem: The term Iran derives directly from Middle Persian Eran, first attested in a 3rd-century inscription at Rustam Relief, with the accompanying Parthian inscription using the term Aryan, in reference to Iranians. The Middle Iranian eran and aryan are oblique plural forms of gentilic er- (Middle Persian) and ary- (Parthian), both deriving from Proto-Iranian *arya- (meaning "Aryan," i.e., "of the Iranians"), argued to descend from Proto-Indo-European *ar-yo-, meaning "skillful assembler." In Iranian languages, the gentilic is attested as a self-identifier included in ancient inscriptions and the literature of Avesta,[a] and remains also in other Iranian ethnic names such as Alans (Ossetic: Ir) and Iron (Ossetic: Iron).
What Proto-Indo-European term means "skillful assembler?"
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Answer: *ar-yo-

Problem: Like aluminium, copper is 100% recyclable without any loss of quality, regardless of whether it is in a raw state or contained in a manufactured product. In volume, copper is the third most recycled metal after iron and aluminium. It is estimated that 80% of the copper ever mined is still in use today. According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of copper in use in society is 3555 kg. Much of this is in more-developed countries (140300 kg per capita) rather than less-developed countries (3040 kg per capita).
What percentage of copper that has been mined is still being used today?
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Answer: 80%

Problem: John Calvin supported the "agent of God" Christology and argued that in his trial in Pilate's Court Jesus could have successfully argued for his innocence, but instead submitted to crucifixion in obedience to the Father. This Christological theme continued into the 20th century, both in the Eastern and Western Churches. In the Eastern Church Sergei Bulgakov argued that the crucifixion of Jesus was "pre-eternally" determined by the Father before the creation of the world, to redeem humanity from the disgrace caused by the fall of Adam. In the Western Church, Karl Rahner elaborated on the analogy that the blood of the Lamb of God (and the water from the side of Jesus) shed at the crucifixion had a cleansing nature, similar to baptismal water.
What is the blood of the lamb?
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Answer:
had a cleansing nature, similar to baptismal water