string(265) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E4%B8%89%E6%9C%AC%E7%99%BD%E7%9A%AE%E4%B9%A6%E7%9A%84%E5%85%A8%E5%90%8D%E5%88%86%E5%88%AB%E6%98%AF => Failed to connect to 14.18.117.71 port 38041: Connection refused"
三本白皮书的全名分别是
