string(249) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E7%9F%AD%E8%B7%AF%E5%92%8C%E6%96%AD%E8%B7%AF%E7%9A%84%E7%A4%BA%E6%84%8F%E5%9B%BE => Failed to connect to 101.89.159.206 port 38100: Connection refused"
短路和断路的示意图
