Article: The armillary sphere, a three-dimensional representation of the movements in the celestial sphere, was invented in Han China by the 1st century BC. Using a water clock, waterwheel and a series of gears, the Court Astronomer Zhang Heng (78–139 AD) was able to mechanically rotate his metal-ringed armillary sphere. To address the problem of slowed timekeeping in the pressure head of the inflow water clock, Zhang was the first in China to install an additional tank between the reservoir and inflow vessel. Zhang also invented a seismometer (Houfeng didong yi 候风地动仪) in 132 AD to detect the exact cardinal or ordinal direction of earthquakes from hundreds of kilometers away. This employed an inverted pendulum that, when disturbed by ground tremors, would trigger a set of gears that dropped a metal ball from one of eight dragon mouths (representing all eight directions) into a metal toad's mouth.

Question: How many dragons were represented in Zhang Heng's invention of the seismometer?
Ans: eight


Article: Many scripts, including Arabic and Devanagari, have special orthographic rules that require certain combinations of letterforms to be combined into special ligature forms. The rules governing ligature formation can be quite complex, requiring special script-shaping technologies such as ACE (Arabic Calligraphic Engine by DecoType in the 1980s and used to generate all the Arabic examples in the printed editions of the Unicode Standard), which became the proof of concept for OpenType (by Adobe and Microsoft), Graphite (by SIL International), or AAT (by Apple).

Question: When was ACE created? 
Ans: 1980s


Article: Meanwhile, Andreas Papandreou founded the Panhellenic Socialist Movement (PASOK) in response to Karamanlis's conservative New Democracy party, with the two political formations alternating in government ever since. Greece rejoined NATO in 1980. Greece became the tenth member of the European Communities (subsequently subsumed by the European Union) on 1 January 1981, ushering in a period of sustained growth. Widespread investments in industrial enterprises and heavy infrastructure, as well as funds from the European Union and growing revenues from tourism, shipping and a fast-growing service sector raised the country's standard of living to unprecedented levels. Traditionally strained relations with neighbouring Turkey improved when successive earthquakes hit both nations in 1999, leading to the lifting of the Greek veto against Turkey's bid for EU membership.

Question: Greece joined what later became the European Union when?
Ans: 1 January 1981


Article: The per capita income of the Republic is often listed as being approximately $400 a year, one of the lowest in the world, but this figure is based mostly on reported sales of exports and largely ignores the unregistered sale of foods, locally produced alcoholic beverages, diamonds, ivory, bushmeat, and traditional medicine. For most Central Africans, the informal economy of the CAR is more important than the formal economy.[citation needed] Export trade is hindered by poor economic development and the country's landlocked position.[citation needed]

Question: Which item that poachers kill elephants for can be obtained in CAR?
Ans:
ivory