Zhongnan Bookstore opens at 8:30 am and closes at 5:30 pm; Dongmen Supermarket opens at 9:00 am and closes at 9:00 pm; Children's Palace opens at 8:00 am and closes at 5:00 pm. Which of them is open the longest and for how long each day?
中南书店上午8：30开门，下午5：30关门；东门超市上午9：00开门，晚上9：00关门；少年宫上午8：00开门，下午5：00关门．他们哪一家开门时间最长，每天营业多长时间？
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