string(269) "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%E5%BB%BA%E6%9C%BA%E7%94%B5%E6%96%B0%E6%97%A7%E6%95%99%E6%9D%90%E5%AF%B9%E6%AF%94 => Failed to connect to 14.18.117.71 port 38220: Connection refused"
2021年二建机电新旧教材对比
