Problem: Greenwich Mean Time (GMT) is an older standard, adopted starting with British railways in 1847. Using telescopes instead of atomic clocks, GMT was calibrated to the mean solar time at the Royal Observatory, Greenwich in the UK. Universal Time (UT) is the modern term for the international telescope-based system, adopted to replace "Greenwich Mean Time" in 1928 by the International Astronomical Union. Observations at the Greenwich Observatory itself ceased in 1954, though the location is still used as the basis for the coordinate system. Because the rotational period of Earth is not perfectly constant, the duration of a second would vary if calibrated to a telescope-based standard like GMT or UTin which a second was defined as a fraction of a day or year. The terms "GMT" and "Greenwich Mean Time" are sometimes used informally to refer to UT or UTC.
How constant is an atomic clock?
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Answer: unanswerable

Problem: Additionally, cable-ready TV sets can display HD content without using an external box. They have a QAM tuner built-in and/or a card slot for inserting a CableCARD.
What kind of card will allow a cable-ready TV to display HD content without an external box?
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Answer: unanswerable

Problem: Bohemia prospered in the 14th century, and the Golden Bull of 1356 made the king of Bohemia first among the imperial electors, but the Hussite revolution threw the country into crisis. The Holy Roman Empire passed to the Habsburgs in 1438, where it remained until its dissolution in 1806. Yet in spite of the extensive territories held by the Habsburgs, the Empire itself remained fragmented, and much real power and influence lay with the individual principalities. In addition, financial institutions, such as the Hanseatic League and the Fugger family, held great power, on both economic and a political levels.
In what year did a Silver Bull make the king of Bohemia first among the imperial electors?
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Answer:
unanswerable