为什么 pip 无法安装包？

Question

我正在尝试安装以下软件包列表：tensorflow-gpu umap-learn visdom webrtcvad librosa>=0.5.1 matplotlib>=2.0.2 numpy>=1.14.0 scipy>=1.0.0 tqdm sounddevice Unidecode inflect PyQt5 multiprocess numba

但是，运行安装命令时出现此错误：

pip install -r requirements.txt
Defaulting to user installation because normal site-packages is not writeable
Collecting tensorflow-gpu
  Using cached tensorflow_gpu-2.2.0rc2-cp38-cp38-manylinux2010_x86_64.whl (516.3 MB)
Collecting umap-learn
  Using cached umap-learn-0.3.10.tar.gz (40 kB)
    ERROR: Command errored out with exit status 1:
     command: /usr/local/bin/python3.8 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-0oapejir/umap-learn/setup.py'"'"'; __file__='"'"'/tmp/pip-install-0oapejir/umap-learn/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-install-0oapejir/umap-learn/pip-egg-info
         cwd: /tmp/pip-install-0oapejir/umap-learn/
    Complete output (11 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/usr/local/lib/python3.8/site-packages/setuptools/__init__.py", line 19, in <module>
        from setuptools.dist import Distribution
      File "/usr/local/lib/python3.8/site-packages/setuptools/dist.py", line 34, in <module>
        from setuptools import windows_support
      File "/usr/local/lib/python3.8/site-packages/setuptools/windows_support.py", line 2, in <module>
        import ctypes
      File "/usr/local/lib/python3.8/ctypes/__init__.py", line 7, in <module>
        from _ctypes import Union, Structure, Array
    ModuleNotFoundError: No module named '_ctypes'
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.