python通过pip安装virtualenv一直报错response.py“, line 438, in _error_catcher yield

G:\ESP32\esp-idf-release-v4.3>pip install virtualenv
Collecting virtualenv
  Downloading virtualenv-20.7.2-py2.py3-none-any.whl (5.3 MB)
     |█                               | 174 kB 4.5 kB/s eta 0:18:56ERROR: Exception:
Traceback (most recent call last):
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\urllib3\response.py", line 438, in _error_catcher
    yield
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\urllib3\response.py", line 519, in read
    data = self._fp.read(amt) if not fp_closed else b""
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\cachecontrol\filewrapper.py", line 62, in read
    data = self.__fp.read(amt)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\http\client.py", line 459, in read
    n = self.readinto(b)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\http\client.py", line 503, in readinto
    n = self.fp.readinto(b)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\socket.py", line 704, in readinto
    return self._sock.recv_into(b)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\ssl.py", line 1241, in recv_into
    return self.read(nbytes, buffer)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\ssl.py", line 1099, in read
    return self._sslobj.read(len, buffer)
socket.timeout: The read operation timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\cli\base_command.py", line 173, in _main
    status = self.run(options, args)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\cli\req_command.py", line 203, in wrapper
    return func(self, options, args)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\commands\install.py", line 315, in run
    requirement_set = resolver.resolve(
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\resolver.py", line 94, in resolve
    result = self._result = resolver.resolve(
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\resolvelib\resolvers.py", line 472, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\resolvelib\resolvers.py", line 341, in resolve
    self._add_to_criteria(self.state.criteria, r, parent=None)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\resolvelib\resolvers.py", line 172, in _add_to_criteria
    if not criterion.candidates:
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\resolvelib\structs.py", line 151, in __bool__
    return bool(self._sequence)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\found_candidates.py", line 140, in __bool__
    return any(self)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\found_candidates.py", line 128, in 
    return (c for c in iterator if id(c) not in self._incompatible_ids)
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\found_candidates.py", line 32, in _iter_built
    candidate = func()
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\factory.py", line 204, in _make_candidate_from_link
    self._link_candidate_cache[link] = LinkCandidate(
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 295, in __init__
    super().__init__(
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 156, in __init__
    self.dist = self._prepare()
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 227, in _prepare
    dist = self._prepare_distribution()
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 305, in _prepare_distribution
    return self._factory.preparer.prepare_linked_requirement(
  File "g:\users\administrator\appdata\local\programs\python\python39\lib\site-packages\pip\_internal\operations\prepare.py", line 508, in prepare_linked_requirement
    return self._prepare_linked_requirement(req, parallel

后来，在系统变量里添加python的路径即可