string(250) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E6%8A%97%E5%8E%8B%E5%BC%BA%E5%BA%A6%E5%8D%95%E4%BD%8D%E6%98%AF%E4%BB%80%E4%B9%88N => Failed to connect to 101.89.143.195 port 38175: Connection refused"
抗压强度单位是什么N
