string(238) "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%E8%AE%A1%E7%AE%97%E5%85%AC%E5%BC%8F => Failed to connect to 61.171.74.35 port 38041: Connection refused"
耐压强度计算公式
