Problem: 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 did return current effect water and gas in iron pipes?
The answer is the following: water and gas mains


In Evita (1996), Madonna played the title role of Eva Perón. For a long time, Madonna had desired to play Perón and wrote to director Alan Parker to explain why she would be perfect for the part. She said later, "This is the role I was born to play. I put everything of me into this because it was much more than a role in a movie. It was exhilarating and intimidating at the same time..... And I am prouder of Evita than anything else I have done." After securing the role, she had vocal training and learned about the history of Argentina and Perón. During shooting she became ill several times due to the intense emotional effort required. However, as she told Oprah, she was also pregnant during the filming: "I was winded after every take. I had to lie on the couch every ten minutes so I could recover from dizzy spells, I was worried that I was shaking the baby around too much and that would injure it in some way." Madonna wrote in her personal diary at the time: "Ironically, this feeling of vulnerability and weakness is helping me in the movie. I'm sure Evita felt this way every day of her life once she discovered she was ill."
When was Madonna pregnant?
During shooting


Input: The Times
The Times is the first newspaper to have borne that name, lending it to numerous other papers around the world, including The Times of India (founded in 1838), The Straits Times (Singapore) (1845), The New York Times (1851), The Irish Times (1859), Le Temps (France) (1861-1942), the Cape Times (South Africa) (1872), the Los Angeles Times (1881), The Seattle Times (1891), The Manila Times (1898), The Daily Times (Malawi) (1900), El Tiempo (Colombia) (1911), The Canberra Times (1926), and The Times (Malta) (1935). In these countries, the newspaper is often referred to as The London Times or The Times of London.

What year did The Times of India start?
Output: 1838


Input: Article: Immanuel Velikovsky is an example of a recent scientific exoheretic; he did not have appropriate scientific credentials or did not publish in scientific journals. While the details of his work are in scientific disrepute, the concept of catastrophic change (extinction event and punctuated equilibrium) has gained acceptance in recent decades.

Now answer this question: What two examples of ideas from Immanuel Velikovsky are stated as to have gained some acceptance?

Output: extinction event and punctuated equilibrium


Article: However, the early Ming government enacted a law, later rescinded, which forbade Han Chinese to learn the tenets of Tibetan Buddhism. There is little detailed evidence of Chinese—especially lay Chinese—studying Tibetan Buddhism until the Republican era (1912–1949). Despite these missions on behalf of the Hongwu Emperor, Morris Rossabi writes that the Yongle Emperor (r. 1402–1424) "was the first Ming ruler actively to seek an extension of relations with Tibet."

Question: What years did the Yongle Emperor reign? 
Ans: 1402–1424


Input: 2008 Sichuan earthquake
In January 2010, Hong Kong-based English newspaper The Standard reported that writer Tan Zuoren attempted to document shoddy construction that may have led to massive casualties in schools, was sentenced to in prison ostensibly for his writing an article in 2007 in support of the pro-democracy movement in 1989.

When did the sentencing occur?
Output:
in 2007