Problem: Please answer a question about the following article about Railway electrification system:
The London Underground in England is one of the few networks that uses a four-rail system. The additional rail carries the electrical return that, on third rail and overhead networks, is provided by the running rails. On the London Underground, a top-contact third rail is beside the track, energized at +420v DC, and a top-contact fourth rail is located centrally between the running rails at 210v DC, which combine to provide a traction voltage of 630v DC. London Underground is now upgrading its fourth rail system to 750v DC with a positive conductor rail energised to +500v DC and a negative conductor rail energised to -250v DC. However, many older sections in tunnels are still energised to 630v DC. The same system was used for Milan's earliest underground line, Milan Metro's line 1, whose more recent lines use an overhead catenary or a third rail.
What is the purpose of the forth rail?
A: carries the electrical return
Problem: Please answer a question about the following article about University:
Their endowment by a prince or monarch and their role in training government officials made these Mediterranean universities similar to Islamic madrasas, although madrasas were generally smaller and individual teachers, rather than the madrasa itself, granted the license or degree. Scholars like Arnold H. Green and Hossein Nasr have argued that starting in the 10th century, some medieval Islamic madrasahs became universities. George Makdisi and others, however, argue that the European university has no parallel in the medieval Islamic world. Other scholars regard the university as uniquely European in origin and characteristics.
In which century did Islamic madrasas start to transform into universities?
A: 10th
Problem: Please answer a question about the following article about Marvel Comics:
In 1971, the United States Department of Health, Education, and Welfare approached Marvel Comics editor-in-chief Stan Lee to do a comic book story about drug abuse. Lee agreed and wrote a three-part Spider-Man story portraying drug use as dangerous and unglamorous. However, the industry's self-censorship board, the Comics Code Authority, refused to approve the story because of the presence of narcotics, deeming the context of the story irrelevant. Lee, with Goodman's approval, published the story regardless in The Amazing Spider-Man #9698 (MayJuly 1971), without the Comics Code seal. The market reacted well to the storyline, and the CCA subsequently revised the Code the same year.
What were the issue dates of the three-episode series on this public health issue?
A: MayJuly 1971
Problem: Please answer a question about the following article about Mali:
Although Mali has enjoyed a reasonably good inter-ethnic relationships based on the long history of coexistence, some hereditary servitude and bondage relationship exist, as well as ethnic tension between settled Songhai and nomadic Tuaregs of the north. Due to a backlash against the northern population after independence, Mali is now in a situation where both groups complain about discrimination on the part of the other group. This conflict also plays a role in the continuing Northern Mali conflict where there is a tension between both Tuaregs and the Malian government, and the Tuaregs and radical Islamists who are trying to establish sharia law.
Songhai and Tuaregs both complain about what same issue towards each other?
A:
discrimination