ImportError：无法导入名称'HTMLAwareEntitySubstitution'

Question

我刚刚设置了beautifulsoup4-4.1.0并将pip升级到版本9.0.1。 当我这样写：

from bs4 import BeautifulSoup

发生

错误：

Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    from bs4 import BeautifulSoup
  File "D:\Program Files (x86)\Python35-32\lib\site-packages\bs4\__init__.py", line 35, in <module>
    from .builder import builder_registry, ParserRejectedMarkup
  File "D:\Program Files (x86)\Python35-32\lib\site-packages\bs4\builder\__init__.py", line 7, in <module>
    from bs4.element import (
ImportError: cannot import name 'HTMLAwareEntitySubstitution'

我该怎么办？非常感谢。