Please answer this: Question: "Why did they need a system to take down a plane with a single hti?" Context: "After the Dambusters raid in 1943 an entirely new system was developed that was required to knock down any low-flying aircraft with a single hit. The first attempt to produce such a system used a 50 mm gun, but this proved inaccurate and a new 55 mm gun replaced it. The system used a centralised control system including both search and targeting radar, which calculated the aim point for the guns after considering windage and ballistics, and then sent electrical commands to the guns, which used hydraulics to point themselves at high speeds. Operators simply fed the guns and selected the targets. This system, modern even by today's standards, was in late development when the war ended." Answer:
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Answer: the Dambusters raid

Problem: Question: "what is been discussed?" Context: "Child labour refers to the employment of children in any work that deprives children of their childhood, interferes with their ability to attend regular school, and that is mentally, physically, socially or morally dangerous and harmful. This practice is considered exploitative by many international organisations. Legislation across the world prohibit child labour. These laws do not consider all work by children as child labour; exceptions include work by child artists, family duties, supervised training, certain categories of work such as those by Amish children, some forms of child work common among indigenous American children, and others." Answer:

A: Child labour

Problem: Given the question: Question: "what is the last amount mentioned?" Context: "Apple spent $2.5 million purchasing all 39 advertising pages in a special, post-election issue of Newsweek, and ran a "Test Drive a Macintosh" promotion, in which potential buyers with a credit card could take home a Macintosh for 24 hours and return it to a dealer afterwards. While 200,000 people participated, dealers disliked the promotion, the supply of computers was insufficient for demand, and many were returned in such a bad condition that they could no longer be sold. This marketing campaign caused CEO John Sculley to raise the price from US$1,995 to US$2,495 (about $5,200 when adjusted for inflation in 2010). The computer sold well, nonetheless, reportedly outselling the IBM PCjr which also began shipping early that year. By April 1984 the company sold 50,000 Macintoshes, and hoped for 70,000 by early May and almost 250,000 by the end of the year." Answer:
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The answer is:
250,000

input question: Question: "What is web hosting?" Context: "Internet services typically provided by ISPs include Internet access, Internet transit, domain name registration, web hosting, Usenet service, and colocation." Answer:???
output answer: Internet services

Question: "__ graduated from Erasmus Hall High School" Context: "Mainstream AC itself has evolved in a similar fashion over the years; traditional AC artists like Barbra Streisand, the Carpenters, Dionne Warwick, Barry Manilow, John Denver, and Olivia Newton-John found it harder to have major Top 40 hits as the 1980s wore on, and due to the influence of MTV, artists who were staples of the Contemporary Hit Radio format, such as Richard Marx, Michael Jackson, Bonnie Tyler, George Michael, Phil Collins, and Laura Branigan began crossing over to the AC charts with greater frequency. Collins has been described by AllMusic as "one of the most successful pop and adult contemporary singers of the '80s and beyond". However, with the combination of MTV and AC radio, adult contemporary appeared harder to define as a genre, with established soft-rock artists of the past still charting pop hits and receiving airplay alongside mainstream radio fare from newer artists at the time." Answer:
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Answer: Barbra Streisand

Q: Question: "What is the Nanjing Library?" Context: "Nanjing Library, founded in 1907, houses more than 10 million volumes of printed materials and is the third largest library in China, after the National Library in Beijing and Shanghai Library. Other libraries, such as city-owned Jinling Library and various district libraries, also provide considerable amount of information to citizens. Nanjing University Library is the second largest university libraries in China after Peking University Library, and the fifth largest nationwide, especially in the number of precious collections." Answer:
A:
third largest library in China