string(226) "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%2Cb2c%2Cc2c%E6%A8%A1%E5%BC%8F => Failed to connect to 14.116.215.7 port 38230: Connection refused"
什么是b2b,b2c,c2c模式
