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Artifacts from the Paleolithic suggest that the moon was used to reckon time as early as 6,000 years ago. Lunar calendars were among the first to appear, either 12 or 13 lunar months (either 354 or 384 days). Without intercalation to add days or months to some years, seasons quickly drift in a calendar based solely on twelve lunar months. Lunisolar calendars have a thirteenth month added to some years to make up for the difference between a full year (now known to be about 365.24 days) and a year of just twelve lunar months. The numbers twelve and thirteen came to feature prominently in many cultures, at least partly due to this relationship of months to years. Other early forms of calendars originated in Mesoamerica, particularly in ancient Mayan civilization. These calendars were religiously and astronomically based, with 18 months in a year and 20 days in a month.
Where did some of the other early forms of months originate?
A: unanswerable

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The Council does not have executive powers but meets biannually to discuss issues of mutual importance. Similarly, the Parliamentary Assembly has no legislative powers but investigates and collects witness evidence from the public on matters of mutual concern to its members. Reports on its findings are presented to the Governments of Ireland and the United Kingdom. During the February 2008 meeting of the British–Irish Council, it was agreed to set up a standing secretariat that would serve as a permanent 'civil service' for the Council. Leading on from developments in the British–Irish Council, the chair of the British–Irish Inter-Parliamentary Assembly, Niall Blaney, has suggested that the body should shadow the British–Irish Council's work.
Reports on the Parliamentary Assembly's findings are presented to the governments of Spain, Ireland and what other country?
A: unanswerable

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Hydrostatic gauges (such as the mercury column manometer) consist of a vertical column of liquid in a tube whose ends are exposed to different pressures. The column will rise or fall until its weight is in equilibrium with the pressure differential between the two ends of the tube. The simplest design is a closed-end U-shaped tube, one side of which is connected to the region of interest. Any fluid can be used, but mercury is preferred for its high density and low vapour pressure. Simple hydrostatic gauges can measure pressures ranging from 1 torr (100 Pa) to above atmospheric. An important variation is the McLeod gauge which isolates a known volume of vacuum and compresses it to multiply the height variation of the liquid column. The McLeod gauge can measure vacuums as high as 10−6 torr (0.1 mPa), which is the lowest direct measurement of pressure that is possible with current technology. Other vacuum gauges can measure lower pressures, but only indirectly by measurement of other pressure-controlled properties. These indirect measurements must be calibrated via a direct measurement, most commonly a McLeod gauge.
What is the lowest amount of mercury that can be measured in the air?
A: unanswerable

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The service's B-2A aircraft entered service in the 1990s, its B-1B aircraft in the 1980s and its current B-52H aircraft in the early 1960s. The B-52 Stratofortress airframe design is over 60 years old and the B-52H aircraft currently in the active inventory were all built between 1960 and 1962. The B-52H is scheduled to remain in service for another 30 years, which would keep the airframe in service for nearly 90 years, an unprecedented length of service for any aircraft. The B-21 is projected to replace the B-52 and parts of the B-1B force by the mid-2020s.
What aircraft in the USAF was introduced in the 1960s?
A:
B-52H