Problem: BeiDou Navigation Satellite System:

In February 2007, the fourth and last satellite of the BeiDou-1 system, BeiDou-1D (sometimes called BeiDou-2A, serving as a backup satellite), was sent up into space. It was reported that the satellite had suffered from a control system malfunction but was then fully restored.

Which satellite is sometimes called BeiDou-2C?
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A: unanswerable


Problem: Alaska:

Another Alaskan transportation method is the dogsled. In modern times (that is, any time after the mid-late 1920s), dog mushing is more of a sport than a true means of transportation. Various races are held around the state, but the best known is the Iditarod Trail Sled Dog Race, a 1,150-mile (1,850 km) trail from Anchorage to Nome (although the distance varies from year to year, the official distance is set at 1,049 miles or 1,688 km). The race commemorates the famous 1925 serum run to Nome in which mushers and dogs like Togo and Balto took much-needed medicine to the diphtheria-stricken community of Nome when all other means of transportation had failed. Mushers from all over the world come to Anchorage each March to compete for cash, prizes, and prestige. The "Serum Run" is another sled dog race that more accurately follows the route of the famous 1925 relay, leaving from the community of Nenana (southwest of Fairbanks) to Nome.

What doesn't the Iditarod Trail Sled Dog Race commemorate in Alaskan history?
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A: unanswerable


Problem: Greece:

With an economy larger than all the Balkan economies combined, Greece is the largest economy in the Balkans, and an important regional investor. Greece is the number-two foreign investor of capital in Albania, the number-three foreign investor in Bulgaria, at the top-three of foreign investors in Romania and Serbia and the most important trading partner and largest foreign investor of the Republic of Macedonia. Greek banks open a new branch somewhere in the Balkans on an almost weekly basis. The Greek telecommunications company OTE has become a strong investor in Yugoslavia and other Balkan countries.

OTE is known as what?
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A: Greek telecommunications company


Problem: Group (mathematics):

In the example above, the identity and the rotations constitute a subgroup R = {id, r1, r2, r3}, highlighted in red in the group table above: any two rotations composed are still a rotation, and a rotation can be undone by (i.e. is inverse to) the complementary rotations 270° for 90°, 180° for 180°, and 90° for 270° (note that rotation in the opposite direction is not defined). The subgroup test is a necessary and sufficient condition for a subset H of a group G to be a subgroup: it is sufficient to check that g−1h ∈ H for all elements g, h ∈ H. Knowing the subgroups is important in understanding the group as a whole.d[›]

270 for 180 is an example of what kind of rotation?
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A:
unanswerable