Python 3.x 在Anaconda安装中使用“jupyter lab”命令获取DLL错误

在Anaconda安装中使用“jupyter lab”命令获取DLL错误：

系统的详细信息：

康达4.5.11 Python 3.7.0 jupyter 4.4.0 奇怪的是，我能够从Anaconda Navigator上启动jupyter实验室，但“jupyter实验室”无法工作，并引发以下异常：

Traceback (most recent call last):
  File "c:\ml\installed_tools\anaconda3\lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "c:\ml\installed_tools\anaconda3\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\ML\installed_tools\anaconda3\Scripts\jupyter-lab.EXE\__main__.py", line 5, in <module>
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\jupyterlab\labapp.py", line 12, in <module>
    from jupyterlab_server import slugify, WORKSPACE_EXTENSION
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\jupyterlab_server\__init__.py", line 4, in <module>
    from .app import LabServerApp
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\jupyterlab_server\app.py", line 9, in <module>
    from .server import ServerApp
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\jupyterlab_server\server.py", line 32, in <module>
    from jupyter_server.serverapp import ServerApp, aliases, flags      # noqa
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\jupyter_server\serverapp.py", line 46, in <module>
    from zmq.eventloop import ioloop
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\zmq\__init__.py", line 47, in <module>
    from zmq import backend
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\zmq\backend\__init__.py", line 40, in <module>
    reraise(*exc_info)
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\zmq\utils\sixcerpt.py", line 34, in reraise
    raise value
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\zmq\backend\__init__.py", line 27, in <module>
    _ns = select_backend(first)
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\zmq\backend\select.py", line 27, in select_backend
    mod = __import__(name, fromlist=public_api)
  File "c:\ml\installed_tools\anaconda3\lib\site-packages\zmq\backend\cython\__init__.py", line 6, in <module>
    from . import (constants, error, message, context,
ImportError: DLL load failed: The specified module could not be found.

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虽然我已经发布了这个问题，但现在我也得到了同样的解决方案

请在path变量中添加以下内容，我刚检查过之后将解决此问题：

C:\ML\installed\u tools\anaconda3已经存在 C:\ML\installed\u tools\anaconda3\Scripts已经存在 C:\ML\installed\u tools\anaconda3\Library\bin现已添加 C:\ML\installed\u tools\anaconda3\Library\mingw-w64\bin现已添加

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什么是路径变量？如何添加到路径变量？