string(276) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E8%80%90%E5%8E%8B%E5%BC%BA%E5%BA%A6%E7%9A%84%E5%8D%95%E4%BD%8D%E6%98%AF%E4%BB%80%E4%B9%88%E7%AC%A6%E5%8F%B7 => Failed to connect to 125.88.227.171 port 38062: Connection refused"
耐压强度的单位是什么符号
