string(277) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E4%BB%80%E4%B9%88%E6%98%AFb2b%E7%94%B5%E5%AD%90%E5%95%86%E5%8A%A1%E6%A8%A1%E5%BC%8F%E7%9A%84%E7%89%B9%E7%82%B9 => Failed to connect to 61.171.74.35 port 38027: Connection refused"
什么是b2b电子商务模式的特点
