string(258) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E4%B8%80%E5%85%83%E4%BA%8C%E6%AC%A1%E8%A7%A3%E6%96%B9%E7%A8%8B%E5%BC%8F%E5%85%AC%E5%BC%8F => Failed to connect to 101.89.143.195 port 38109: Connection refused"
一元二次解方程式公式
