bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: 的解决方法

爬虫dom = BeautifulSoup(html, "lxml")  # 解析html文档时出现错误如下：

bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml. Do you need。。。

错误原因：

bs4调用了python自带的html解析器，而版本python3未带有该解析器，需要重新pip下载。

解决方法：

     

pip install lxml

问题完美解决。