Task: Question Generation
Input (English): The annual United States Open Tennis Championships is one of the world's four Grand Slam tennis tournaments and is held at the National Tennis Center in Flushing Meadows-Corona Park, Queens. The New York Marathon is one of the world's largest, and the 2004–2006 events hold the top three places in the marathons with the largest number of finishers, including 37,866 finishers in 2006. The Millrose Games is an annual track and field meet whose featured event is the Wanamaker Mile. Boxing is also a prominent part of the city's sporting scene, with events like the Amateur Boxing Golden Gloves being held at Madison Square Garden each year. The city is also considered the host of the Belmont Stakes, the last, longest and oldest of horse racing's Triple Crown races, held just over the city's border at Belmont Park on the first or second Sunday of June. The city also hosted the 1932 U.S. Open golf tournament and the 1930 and 1939 PGA Championships, and has been host city for both events several times, most notably for nearby Winged Foot Golf Club.
Output (English): What tennis Grand Slam event is held at the National Tennis Center?