string(265) "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%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4 => Failed to connect to 61.171.74.35 port 38041: Connection refused"
生产能力指数的取值范围
