Problem: The CD was planned to be the successor of the gramophone record for playing music, rather than primarily as a data storage medium. From its origins as a musical format, CDs have grown to encompass other applications. In 1983, following the CD's introduction, Immink and Braat presented the first experiments with erasable compact discs during the 73rd AES Convention. In June 1985, the computer-readable CD-ROM (read-only memory) and, in 1990, CD-Recordable were introduced, also developed by both Sony and Philips. Recordable CDs were a new alternative to tape for recording music and copying music albums without defects introduced in compression used in other digital recording methods. Other newer video formats such as DVD and Blu-ray use the same physical geometry as CD, and most DVD and Blu-ray players are backward compatible with audio CD.
What does ROM stand for?
The answer is the following: read-only memory

Problem: At the beginning of World War I, East Prussia became a theatre of war when the Russian Empire invaded the country. The Russian Army encountered at first little resistance because the bulk of the German Army had been directed towards the Western Front according to the Schlieffen Plan. Despite early success and the capture of the towns of Rastenburg and Gumbinnen, in the Battle of Tannenberg in 1914 and the Second Battle of the Masurian Lakes in 1915, the Russians were decisively defeated and forced to retreat. The Russians were followed by the German Army advancing into Russian territory.
Which country invaded east Prussia in World War I?
The answer is the following: Russian Empire

Problem: During the century of internecine struggles for dominance among the Northern Christians kingdoms, the County of Portugal, formed the southern portion of the Kingdom of Galicia. At times the Kingdom of Galicia existed independently for short periods, but usually formed an important part of the Kingdom of Leon. Throughout this period, the people of County of Portugal as Galicians found themselves struggling to maintain the autonomy of Galicia with its distinct language and culture (Galician-Portuguese) from the Leonese culture, whenever the status of the Kingdom of Galicia changed in relation to the Kingdom of Leon. As a result of political division, Galician-Portuguese lost its unity when the County of Portugal separated from the Kingdom of Galicia (a dependent kingdom of Leon) to establish the Kingdom of Portugal. The Galician and Portuguese versions of the language then diverged over time as they followed independent evolutionary paths. This began occurring when the Kingdom of Leon and the Kingdom of Castile united and the Castilian Language (known as Spanish) slowly over the centuries began influencing the Galician Language and then trying to replace it. The same thing happened to Astur-Leonese Language to the point where it is greatly reduced or completely replaced by the Castilian (Spanish Language).
During the internecine struggles, what did the the people of Country of Portugal struggle with?
The answer is the following: maintain the autonomy of Galicia with its distinct language and culture (Galician-Portuguese) from the Leonese culture

Problem: Some of the earliest recorded observations ever made through a telescope, Galileo's drawings on 28 December 1612 and 27 January 1613, contain plotted points that match up with what is now known to be the position of Neptune. On both occasions, Galileo seems to have mistaken Neptune for a fixed star when it appeared close—in conjunction—to Jupiter in the night sky; hence, he is not credited with Neptune's discovery. At his first observation in December 1612, Neptune was almost stationary in the sky because it had just turned retrograde that day. This apparent backward motion is created when Earth's orbit takes it past an outer planet. Because Neptune was only beginning its yearly retrograde cycle, the motion of the planet was far too slight to be detected with Galileo's small telescope. In July 2009, University of Melbourne physicist David Jamieson announced new evidence suggesting that Galileo was at least aware that the 'star' he had observed had moved relative to the fixed stars.
What happens when Neptune goes retrograde? 
The answer is the following:
Earth's orbit takes it past an outer planet