在网页中取出图片网址：
re.search(r"http.+?\.jpg",s).group()
提取域名前面的网址：s = https://blog.csdn.net/wangshuai33/article/details/82963081
re.sub(r"(http://.+?/).*",lambda x: x.group(1),s)
一个句子里找出所有单词：s = "swfk wfhweu efee"
re.split(r" +",s)
["swfk wfhweu efee"]
re.findall(r"\b[a-zA-Z]+\b",s)
["swfk wfhweu efee"]