[问答题] 简述经济学的均衡原理。

生物心理社会医学模式 交响乐团通常由（）三大声部组成。 ["管乐、弦乐、钢琴","弦乐、管乐、打击乐","管乐、钢琴、打击乐","弦乐、钢琴、打击乐"] 杂草危害经济阈值 路基的要求的原因？ On which options are standard access lists based?（） ["destination address and wildcard mask","source address and wildcard mask","destination address and subnet mask","source address and subnet mask"] 简述经济学的均衡原理。