html=""" #注意，第一次写，缩进了一点点，python对格式十分注重。。
<html><head><title>the dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><b>the dormouse's story</b></p>
<p class="story">once upon a time there were three little sisters;and their names were
<a href="http//example.com/elsie" class="sister" id="link1"><!--elsie--></a>
<a href="http://example.com/lacie" class="sister" id="link2">lacie</a>and
<a href="http://example.com/title" class="sister" id="link3">title</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""
soup=BeautifulSoup(html,"lxml") #注意：括号里的html没有“”，第一次加了双引号。。
print(soup.prettify()) #prettify()可以自己把html代码格式调整好。
print(soup.title.string) #输出title里面的字符。。
出错：就是因为soup=BeautifulSoup("html","lxml") html多加了“”