错误的pip3 python位置

我在Ubuntu/Linux上

我尝试用最新版本安装python3.8.2

在我安装之前，我有3.5.2版，而且运行得很好

但现在pip和pip3是相同的链接位置：

pip -V
pip 20.0.2 from /usr/local/lib/python3.8/site-packages/pip (python 3.8)
pip3 -V
pip 20.0.2 from /usr/local/lib/python3.8/site-packages/pip (python 3.8)

问题是为什么我无法安装任何带有新版本错误消息的软件包，错误消息显示： **

sudopip3安装nltk

**

（pip3列表）

步骤1:

我怎样才能带着pip3回到python3

第二步：

如何修复错误以便使用3.8.2

你会怎么做？：）

谢谢您抽出时间来

WARNING: The directory '/home/fredy/.cache/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting nltk
  Downloading nltk-3.4.5.zip (1.5 MB)
     |████████████████████████████████| 1.5 MB 2.3 MB/s 
    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-d0mx8gb1/nltk/setup.py'"'"'; __file__='"'"'/tmp/pip-install-d0mx8gb1/nltk/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-d0mx8gb1/nltk/pip-egg-info
         cwd: /tmp/pip-install-d0mx8gb1/nltk/
    Complete output (11 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/home/fredy/.local/lib/python3.8/site-packages/setuptools/__init__.py", line 19, in <module>
        from setuptools.dist import Distribution
      File "/home/fredy/.local/lib/python3.8/site-packages/setuptools/dist.py", line 34, in <module>
        from setuptools import windows_support
      File "/home/fredy/.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.

Package    Version
---------- -------
pip        20.0.2 
setuptools 46.1.1

Package    Version
---------- -------
pip        20.0.2 
setuptools 46.1.1