Problem: Railway electrification system:

The key advantage of the four-rail system is that neither running rail carries any current. This scheme was introduced because of the problems of return currents, intended to be carried by the earthed (grounded) running rail, flowing through the iron tunnel linings instead. This can cause electrolytic damage and even arcing if the tunnel segments are not electrically bonded together. The problem was exacerbated because the return current also had a tendency to flow through nearby iron pipes forming the water and gas mains. Some of these, particularly Victorian mains that predated London's underground railways, were not constructed to carry currents and had no adequate electrical bonding between pipe segments. The four-rail system solves the problem. Although the supply has an artificially created earth point, this connection is derived by using resistors which ensures that stray earth currents are kept to manageable levels. Power-only rails can be mounted on strongly insulating ceramic chairs to minimise current leak, but this is not possible for running rails which have to be seated on stronger metal chairs to carry the weight of trains. However, elastomeric rubber pads placed between the rails and chairs can now solve part of the problem by insulating the running rails from the current return should there be a leakage through the running rails.

How are stray earth currents kept to a manageable levels?
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A: by using resistors

Problem: In the spring of 1854 the Russians again advanced, crossing the Danube River into the Turkish province of Dobruja. By April 1854, the Russians had reached the lines of Trajan's Wall where they were finally halted. In the center, the Russian forces crossed the Danube and laid siege to Silistra from 14 April with 60,000 troops, the defenders with 15,000 had supplies for three months.:415 The siege was lifted on 23 June 1854. The English and French forces at this time were unable to take the field for lack of equipment.:415
Why couldn't the French and English take control of the field?
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Answer: lack of equipment

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".

Australia: The event was held in Canberra, Australian Capital Territory on April 24, and covered around 16 km of Canberra's central areas, from Reconciliation Place to Commonwealth Park. Upon its arrival in Canberra, the Olympic flame was presented by Chinese officials to local Aboriginal elder Agnes Shea, of the Ngunnawal people. She, in turn, offered them a message stick, as a gift of peace and welcome. Hundreds of pro-Tibet protesters and thousands of Chinese students reportedly attended. Demonstrators and counter-demonstrators were kept apart by the Australian Federal Police. Preparations for the event were marred by a disagreement over the role of the Chinese flame attendants, with Australian and Chinese officials arguing publicly over their function and prerogatives during a press conference.
What did Agnes Shea give to the Chinese in return?
A: a message stick

Context and question: Media outlets began reporting in late September 2009 that Comcast was in talks to buy NBCUniversal. Comcast denied the rumors at first, while NBC would not comment on them. However, CNBC itself reported on October 1 that General Electric was considering spinning NBCUniversal off into a separate company that would merge the NBC television network and its cable properties such as USA Network, Syfy and MSNBC with Comcast's content assets. GE would maintain 49% control of the new company, while Comcast owned 51%. Vivendi, which owns 20%, would have to sell its stake to GE. It was reported that under the current deal with GE that it would happen in November or December. It was also reported that Time Warner would be interested in placing a bid, until CEO Jeffrey L. Bewkes directly denied interest, leaving Comcast the sole bidder. On November 1, 2009, The New York Times reported Comcast had moved closer to a deal to purchase NBCUniversal and that a formal announcement could be made sometime the following week.
What was NBC's parent company in 2009?
Answer: General Electric

Question: In the year 1563 the influential Ecumenical Council of Trent, headed by Pope Pius IV, wrote about the importance of selecting good Cardinals. According to this historic council "nothing is more necessary to the Church of God than that the holy Roman pontiff apply that solicitude which by the duty of his office he owes the universal Church in a very special way by associating with himself as cardinals the most select persons only, and appoint to each church most eminently upright and competent shepherds; and this the more so, because our Lord Jesus Christ will require at his hands the blood of the sheep of Christ that perish through the evil government of shepherds who are negligent and forgetful of their office."
Is there an answer to this question: In what year did the Ecumenical Council of Trent write in regards to the selection of Cardinals?

Answer: 1563

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Until 2005, the United Nations General Assembly annually adopted a detailed resolution about the situation in Myanmar by consensus. But in 2006 a divided United Nations General Assembly voted through a resolution that strongly called upon the government of Myanmar to end its systematic violations of human rights. In January 2007, Russia and China vetoed a draft resolution before the United Nations Security Council calling on the government of Myanmar to respect human rights and begin a democratic transition. South Africa also voted against the resolution.
What did China and Russia both do in 2008 ?
A:
vetoed a draft resolution before the United Nations Security Council calling on the government of Myanmar