Please answer this: Extract the answer to the question from the following context. Question: How many stations and rail lines are there in the combined network? Context: New York City's commuter rail network is the largest in North America. The rail network, connecting New York City to its suburbs, consists of the Long Island Rail Road, Metro-North Railroad, and New Jersey Transit. The combined systems converge at Grand Central Terminal and Pennsylvania Station and contain more than 250 stations and 20 rail lines. In Queens, the elevated AirTrain people mover system connects JFK International Airport to the New York City Subway and the Long Island Rail Road; a separate AirTrain system is planned alongside the Grand Central Parkway to connect LaGuardia Airport to these transit systems. For intercity rail, New York City is served by Amtrak, whose busiest station by a significant margin is Pennsylvania Station on the West Side of Manhattan, from which Amtrak provides connections to Boston, Philadelphia, and Washington, D.C. along the Northeast Corridor, as well as long-distance train service to other North American cities.
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Answer: more than 250 stations and 20 rail lines

Please answer this: Extract the answer to the question from the following context. Question: what is the first time period mentioned? Context: From the 1987 season until the late 1990s, the most exposure the league would receive was on ESPN, which aired tape-delayed games, often well after midnight, and often edited to match the alloted time slot. The league received its first taste of wide exposure in 1998, when Arena Bowl XII was televised nationally as part of ABC's old Wide World of Sports.
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Answer: 1987

Please answer this: Extract the answer to the question from the following context. Question: What is the main point of the passage? Context: A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon. Some solar balloons are large enough for human flight, but usage is generally limited to the toy market as the surface-area to payload-weight ratio is relatively high.
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Answer:
Some solar balloons are large enough for human flight, but usage is generally limited