Here is a question about this article: A plethora of anti-aircraft gun systems of smaller calibre were available to the German Wehrmacht combined forces, and among them the 1940-origin Flakvierling quadruple-20 mm-gun antiaircraft weapon system was one of the most often-seen weapons, seeing service on both land and sea. The similar Allied smaller-calibre air-defence weapons systems of the American forces were also quite capable, although they receive little attention. Their needs could cogently be met with smaller-calibre ordnance beyond using the usual singly-mounted M2 .50 caliber machine gun atop a tank's turret, as four of the ground-used "heavy barrel" (M2HB) guns were mounted together on the American Maxson firm's M45 Quadmount weapons system (as a direct answer to the Flakvierling),which were often mounted on the back of a half-track to form the Half Track, M16 GMC, Anti-Aircraft. Although of less power than Germany's 20 mm systems, the typical 4 or 5 combat batteries of an Army AAA battalion were often spread many kilometers apart from each other, rapidly attaching and detaching to larger ground combat units to provide welcome defence from enemy aircraft.
What is the answer to this question: How many of the M2HB guns were mounted together on the M45 Quadmount weapons system?
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So... four

Here is a question about this article: PAL, SECAM and NTSC frame rates technically apply only to analogue standard definition television, not to digital or high definition broadcasts. However, with the roll out of digital broadcasting, and later HDTV broadcasting, countries retained their heritage systems. HDTV in former PAL and SECAM countries operates at a frame rate of 25/50 Hz, while HDTV in former NTSC countries operates at 30/60 Hz.
What is the answer to this question: PAL, SECAM, and NTSC frame rates do not apply to what broadcasts?
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So... digital or high definition

Here is a question about this article: 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 is the answer to this question: What other term in the 3rd Century besides Aryan also refer to Iran?
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So...
Eran