Question: Question: "What country pushed the boundaries for railway power delivery?" Context: "There has, however, been interest among railroad operators in returning to DC use at higher voltages than previously used. At the same voltage, DC often has less loss than AC, and for this reason high-voltage direct current is already used on some bulk power transmission lines. DC avoids the electromagnetic radiation inherent with AC, and on a railway this also reduces interference with signalling and communications and mitigates hypothetical EMF risks. DC also avoids the power factor problems of AC. Of particular interest to railroading is that DC can supply constant power with a single ungrounded wire. Constant power with AC requires three-phase transmission with at least two ungrounded wires. Another important consideration is that mains-frequency 3-phase AC must be carefully planned to avoid unbalanced phase loads. Parts of the system are supplied from different phases on the assumption that the total loads of the 3 phases will even out. At the phase break points between regions supplied from different phases, long insulated supply breaks are required to avoid them being shorted by rolling stock using more than one pantograph at a time. A few railroads have tried 3-phase but its substantial complexity has made single-phase standard practice despite the interruption in power flow that occurs twice every cycle. An experimental 6 kV DC railway was built in the Soviet Union." Answer:
Answer: Soviet Union

Question: Question: "What constitutes the museum?" Context: "Philadelphia's major science museums include the Franklin Institute, which contains the Benjamin Franklin National Memorial; the Academy of Natural Sciences; the Mutter Museum; and the University of Pennsylvania Museum of Archaeology and Anthropology. History museums include the National Constitution Center, the Atwater Kent Museum of Philadelphia History, the National Museum of American Jewish History, the African American Museum in Philadelphia, the Historical Society of Pennsylvania, the Grand Lodge of Free and Accepted Masons in the state of Pennsylvania and The Masonic Library and Museum of Pennsylvania and Eastern State Penitentiary. Philadelphia is home to the United States' first zoo and hospital, as well as Fairmount Park, one of America's oldest and largest urban parks." Answer:
Answer: Benjamin Franklin National Memorial; the Academy of Natural Sciences; the Mutter Museum; and the University of Pennsylvania Museum of Archaeology and Anthropology

Question: Question: "How did Apple address the main problem users experienced with the first generation iPod?" Context: "iPods have been criticized for alleged short life-span and fragile hard drives. A 2005 survey conducted on the MacInTouch website found that the iPod line had an average failure rate of 13.7% (although they note that comments from respondents indicate that "the true iPod failure rate may be lower than it appears"). It concluded that some models were more durable than others. In particular, failure rates for iPods employing hard drives was usually above 20% while those with flash memory had a failure rate below 10%. In late 2005, many users complained that the surface of the first generation iPod Nano can become scratched easily, rendering the screen unusable. A class action lawsuit was also filed. Apple initially considered the issue a minor defect, but later began shipping these iPods with protective sleeves.[citation needed]" Answer:
Answer:
began shipping these iPods with protective sleeves