Nltk: https://raw.githubusercontent.com/nltk/nltk_data/gh-pages/index.xml에 문제가 있습니다.

xml 온라인 유효성 검사기에서 다음과 같이 말합니다.

An error has been found! 
Click on  to jump to the error. In the document, you can point at  with your mouse to see the error message. 
Errors in file xml-schema: 
    23: 144 Attribute name "unzipped_size" associated with an element type "package" must be followed by the ' = ' character.

python3에서 stopwords 를 다운로드하려고 할 때

import nltk
nltk.download('stopwords')

오류가 발생했습니다

>>> import nltk
>>> nltk.download('stopwords')

Traceback (most recent call last):
  File "/usr/lib/python3.5/code.py", line 91, in runcode
    exec(code, self.locals)
  File "<input>", line 1, in <module>
  File "/usr/local/lib/python3.5/dist-packages/nltk/downloader.py", line 664, in download
    for msg in self.incr_download(info_or_id, download_dir, force):
  File "/usr/local/lib/python3.5/dist-packages/nltk/downloader.py", line 534, in incr_download
    try: info = self._info_or_id(info_or_id)
  File "/usr/local/lib/python3.5/dist-packages/nltk/downloader.py", line 508, in _info_or_id
    return self.info(info_or_id)
  File "/usr/local/lib/python3.5/dist-packages/nltk/downloader.py", line 875, in info
    self._update_index()
  File "/usr/local/lib/python3.5/dist-packages/nltk/downloader.py", line 825, in _update_index
    ElementTree.parse(compat.urlopen(self._url)).getroot())
  File "/usr/lib/python3.5/xml/etree/ElementTree.py", line 1184, in parse
    tree.parse(source, parser)
  File "/usr/lib/python3.5/xml/etree/ElementTree.py", line 596, in parse
    self._root = parser._parse_whole(source)
xml.etree.ElementTree.ParseError: not well-formed (invalid token): line 23, column 143

당신의 XML 에서
<package checksum="6f9c042774b96366c93fd0f9a9adb697" id="dolch" name="Dolch Word List" size="2116" subdir="corpora" unzip="1" unzipped_size"1917" url="https://en.wikipedia.org/wiki/Dolch_word_list" />

unzipped_size"1917"은 unzipped_size="1917" 이어야 합니다.
누락된 등호