2011-2-17号，中国阴历15号，也是法律规定北京市五环内最后放炮的一天。吴昊昊在这天把两个红色的大炮放在安定门的大鼎上，并点燃。17th February, 2011, 15th on the Chinese calendar, it's also the last day for firecrackers by law.Wu Haohao put two big red crackers on the ding-cauldron at Anding Gate. Then set them off.