Problem: Kievan Rus%27:

The Chronicle reports that Askold and Dir continued to Constantinople with a navy to attack the city in 863–66, catching the Byzantines by surprise and ravaging the surrounding area, though other accounts date the attack in 860. Patriarch Photius vividly describes the "universal" devastation of the suburbs and nearby islands, and another account further details the destruction and slaughter of the invasion. The Rus' turned back before attacking the city itself, due either to a storm dispersing their boats, the return of the Emperor, or in a later account, due to a miracle after a ceremonial appeal by the Patriarch and the Emperor to the Virgin. The attack was the first encounter between the Rus' and Byzantines and led the Patriarch to send missionaries north to engage and attempt to convert the Rus' and the Slavs.

What did the attack between Rus and Byzantines lead to?
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A: Patriarch to send missionaries north to engage


Problem: European Central Bank:

Although the ECB is governed by European law directly and thus not by corporate law applying to private law companies, its set-up resembles that of a corporation in the sense that the ECB has shareholders and stock capital. Its capital is five billion euros which is held by the national central banks of the member states as shareholders. The initial capital allocation key was determined in 1998 on the basis of the states' population and GDP, but the key is adjustable. Shares in the ECB are not transferable and cannot be used as collateral.

What determined the ECB's initial capital?
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A: the basis of the states' population and GDP


Problem: Infection:

Technologies based upon the polymerase chain reaction (PCR) method will become nearly ubiquitous gold standards of diagnostics of the near future, for several reasons. First, the catalog of infectious agents has grown to the point that virtually all of the significant infectious agents of the human population have been identified. Second, an infectious agent must grow within the human body to cause disease; essentially it must amplify its own nucleic acids in order to cause a disease. This amplification of nucleic acid in infected tissue offers an opportunity to detect the infectious agent by using PCR. Third, the essential tools for directing PCR, primers, are derived from the genomes of infectious agents, and with time those genomes will be known, if they are not already.

What does the acronym PCR expand to?
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A: polymerase chain reaction


Problem: BeiDou Navigation Satellite System:

The investigation of the transmitted signals started immediately after the launch of Compass -M1 on 14 April 2007. Soon after in June 2007, engineers at CNES reported the spectrum and structure of the signals. A month later, researchers from Stanford University reported the complete decoding of the “I” signals components. The knowledge of the codes allowed a group of engineers at Septentrio to build the COMPASS receiver and report tracking and multipath characteristics of the “I” signals on E2 and E5B.

Knowing the codes allowed Stanford researchers to build the NERF receiver and report what? 
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A:
unanswerable