string(257) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%8E%86%E5%B9%B4%E4%B8%AD%E5%9B%BD%E6%8C%81%E6%9C%89%E7%BE%8E%E5%80%BA%E6%83%85%E5%86%B5 => Failed to connect to 101.91.112.32 port 38195: Connection refused"
历年中国持有美债情况
