The portraits of the twelve students were originally on the 12 stone platform of the fan-shaped pool water fountain in front of the Haiyan Church in the Yuanmingyuan. These portraits are human heads, the head is copper, the body is stone, and the hollow is connected to the water spray pipe. Every other The hour, the portrait of the child representing that hour, sprayed water from his mouth; at noon, the fountain of twelve portraits burst into the mouth at the same time. First, this batch of national treasures has been lost overseas for more than a century. According to this text, the actual use of the portraits of the twelve lives is (). ['Adjust the humidity of the garden air.', 'Water spraying device in fan-shaped pool.', 'Role of reporting time.', 'Luxury ornamentals in the Royal Gardens.']