QUES: In December 2011, the system went into operation on a trial basis. It has started providing navigation, positioning and timing data to China and the neighbouring area for free from 27 December. During this trial run, Compass will offer positioning accuracy to within 25 meters, but the precision will improve as more satellites are launched. Upon the system's official launch, it pledged to offer general users positioning information accurate to the nearest 10 m, measure speeds within 0.2 m per second, and provide signals for clock synchronisation accurate to 0.02 microseconds.
When did the Compass system begin operation on a trial bases?

ANS: December 2011

QUES: Large masses, such as ice sheets or glaciers, can depress the crust of the Earth into the mantle. The depression usually totals a third of the ice sheet or glacier's thickness. After the ice sheet or glacier melts, the mantle begins to flow back to its original position, pushing the crust back up. This post-glacial rebound, which proceeds very slowly after the melting of the ice sheet or glacier, is currently occurring in measurable amounts in Scandinavia and the Great Lakes region of North America.
What happens quickly after the ice sheet melts?

ANS: unanswerable

QUES: The Prussian General Staff developed by Moltke proved to be extremely effective, in contrast to the traditional French school. This was in large part due to the fact that the Prussian General Staff was created to study previous Prussian operations and learn to avoid mistakes. The structure also greatly strengthened Moltke's ability to control large formations spread out over significant distances. The Chief of the General Staff, effectively the commander in chief of the Prussian army, was independent of the minister of war and answered only to the monarch. The French General Staffalong with those of every other European militarywas little better than a collection of assistants for the line commanders. This disorganization hampered the French commanders' ability to exercise control of their forces.
What was key factor did the Prussian General Staff study?

ANS: previous Prussian operations

QUES: While outer space provides the most rarefied example of a naturally occurring partial vacuum, the heavens were originally thought to be seamlessly filled by a rigid indestructible material called aether. Borrowing somewhat from the pneuma of Stoic physics, aether came to be regarded as the rarefied air from which it took its name, (see Aether (mythology)). Early theories of light posited a ubiquitous terrestrial and celestial medium through which light propagated. Additionally, the concept informed Isaac Newton's explanations of both refraction and of radiant heat. 19th century experiments into this luminiferous aether attempted to detect a minute drag on the Earth's orbit. While the Earth does, in fact, move through a relatively dense medium in comparison to that of interstellar space, the drag is so minuscule that it could not be detected. In 1912, astronomer Henry Pickering commented: "While the interstellar absorbing medium may be simply the ether, [it] is characteristic of a gas, and free gaseous molecules are certainly there".
Where did the ideas about the properties of molecules come from?

ANS:
unanswerable