假设要给以下 HTML 代码中的 div 标签中的文本添加 br 标签：

    
This is the first line of text.
    
This is the second line of text.
    
This is the third line of text.

可以使用 Beautiful Soup 库来解决该问题，示例如下：

from bs4 import BeautifulSoup, NavigableString

html = """
    

        
This is the first line of text.
        
This is the second line of text.
        
This is the third line of text.
    
"""

soup = BeautifulSoup(html, 'html.parser')
div = soup.find('div', {'class': 'text'})
new_content = []

for content in div.contents:
    if isinstance(content, NavigableString):
        lines = content.strip().split('\n')
        for line in lines:
            new_content.append(line)
            new_content.append(soup.new_tag('br'))
    else:
        new_content.append(content)

div.contents = new_content

print(soup.prettify())

输出结果如下：

 

  This is the first line of text.
 
 

 

  This is the second line of text.
 
 

 

  This is the third line of text.
 
 

可以看到，成功地在 div 中的文本中添加了 br 标签。