string(292) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E6%95%B0%E5%AD%A6%E4%B8%AD%E5%87%8F%E6%95%B0%E5%92%8C%E8%A2%AB%E5%87%8F%E6%95%B0%E4%B9%8B%E9%97%B4%E7%9A%84%E5%85%B3%E7%B3%BB => Failed to connect to 14.18.117.71 port 38041: Connection refused"
数学中减数和被减数之间的关系
