string(249) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%A4%8D%E6%95%B0%E4%B9%98%E9%99%A4%E6%B3%95%E8%BF%90%E7%AE%97%E6%8A%80%E5%B7%A7 => Failed to connect to 101.89.117.144 port 38056: Connection refused"
复数乘除法运算技巧
