Problem: The 1775 treatise "The Natural Varieties of Mankind", by Johann Friedrich Blumenbach proposed five major divisions: the Caucasoid race, Mongoloid race, Ethiopian race (later termed Negroid, and not to be confused with the narrower Ethiopid race), American Indian race, and Malayan race, but he did not propose any hierarchy among the races. Blumenbach also noted the graded transition in appearances from one group to adjacent groups and suggested that "one variety of mankind does so sensibly pass into the other, that you cannot mark out the limits between them".
What can one not mark between the variety of mankind?
The answer is the following: limits

Problem: Motors have very little room for electrical insulation so they generally have low voltage ratings. Because transformers (prior to the development of power electronics) cannot step down DC voltages, trains were supplied with a relatively low DC voltage that the motors can use directly. The most common DC voltages are listed in the previous section. Third (and fourth) rail systems almost always use voltages below 1 kV for safety reasons while overhead wires usually use higher voltages for efficiency. ("Low" voltage is relative; even 600 V can be instantly lethal when touched.)
Which system uses higher voltages?
The answer is the following: overhead wires

Problem: The Quranic content is concerned with basic Islamic beliefs including the existence of God and the resurrection. Narratives of the early prophets, ethical and legal subjects, historical events of Muhammad's time, charity and prayer also appear in the Quran. The Quranic verses contain general exhortations regarding right and wrong and historical events are related to outline general moral lessons. Verses pertaining to natural phenomena have been interpreted by Muslims as an indication of the authenticity of the Quranic message.
Quranic verses concerning which phenomena are thought by Muslims to authenticate its contents?
The answer is the following: natural

Problem: Federally, Boston is split between two congressional districts. The northern three-fourths of the city is in the 7th district, represented by Mike Capuano since 1998. The southern fourth is in the 8th district, represented by Stephen Lynch. Both are Democrats; a Republican has not represented a significant portion of Boston in over a century. The state's senior member of the United States Senate is Democrat Elizabeth Warren, first elected in 2012. The state's junior member of the United States Senate is Democrat Ed Markey, who was elected in 2013 to succeed John Kerry after Kerry's appointment and confirmation as the United States Secretary of State.
What district is the South fourth of Boston located in?
The answer is the following:
the 8th district