context: Alberto Ascari (Italian: Alberto Ascari; July 13, 1918, Milan - May 26, 1955, Monza) - a hereditary Italian race car driver, Formula 1 champion in 1952 and 1953. He is the second and so far the last Italian who managed to win this title. He won both titles, speaking for the Ferrari team. He participated in only 33 races, but managed to set many records, some of them have not been beaten so far. After several extremely successful years he moved to the Lancia team, where he was engaged in fine-tuning a promising car, but after a year and a half of work he died under unclear circumstances, testing a sports car on the Monza highway.
question: How did Alberto Ascari die?
answers.text: unclear circumstances, testing a sports car on the Monza highway