string(280) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=2021%E5%B9%B4%E4%BA%8C%E7%BA%A7%E5%BB%BA%E9%80%A0%E5%B8%88%E6%B0%B4%E5%88%A9%E6%95%99%E6%9D%90%E5%8F%98%E5%8C%96 => Failed to connect to 101.89.117.144 port 38005: Connection refused"
2021年二级建造师水利教材变化
