string(285) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E7%BD%91%E7%BB%9C%E8%90%A5%E9%94%80%E7%9A%84%E7%89%B9%E7%82%B9%E4%B8%BB%E8%A6%81%E5%8C%85%E6%8B%AC%E4%BB%80%E4%B9%88 => Failed to connect to 101.89.159.206 port 38087: Connection refused"
网络营销的特点主要包括什么
