string(255) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=2021%E4%B8%80%E5%BB%BA%E6%95%99%E6%9D%90%E5%92%8C2020%E5%B9%B4%E7%9A%84%E5%8C%BA%E5%88%AB => Failed to connect to 14.18.117.71 port 38220: Connection refused"
2021一建教材和2020年的区别
