string(274) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E7%94%9F%E4%BA%A7%E8%83%BD%E5%8A%9B%E6%8C%87%E6%95%B0%E6%B3%95%E5%A4%9A%E7%94%A8%E4%BA%8E%E4%BC%B0%E7%AE%97 => Failed to connect to 14.116.215.7 port 38230: Connection refused"
生产能力指数法多用于估算
