由于pip19.2.3版本诸多问题， 决定卸载， 结果发现根本无法卸载， 提示以下错误信息：
C:Usersabc>python -m pip uninstall pipUninstalling pip-19.2.3: Would remove: c:program filespython38libsite-packagespip-19.2.3.dist-info* c:program filespython38libsite-packagespip* c:program filespython38scriptspip.exe c:program filespython38scriptspip3.8.exe c:program filespython38scriptspip3.exeProceed (y/n)? yERROR: Exception:Traceback (most recent call last): File "C:Program FilesPython38libshutil.py", line 781, in move os.rename(src, real_dst)PermissionError: [WinError 5] 拒绝访问。: 'c:\program files\python38\lib\site-packages\pip-19.2.3.dist-info\' -> 'C:\Users\abc\AppData\Local\Temp\pip-uninstall-flz7sdgb'During handling of the above exception, another exception occurred:Traceback (most recent call last): File "C:Program FilesPython38libsite-packagespip_internalclibase_command.py", line 188, in main status = self.run(options, args) File "C:Program FilesPython38libsite-packagespip_internalcommandsuninstall.py", line 74, in run uninstall_pathset = req.uninstall( File "C:Program FilesPython38libsite-packagespip_internalreqreq_install.py", line 831, in uninstall uninstalled_pathset.remove(auto_confirm, verbose) File "C:Program FilesPython38libsite-packagespip_internalreqreq_uninstall.py", line 388, in remove moved.stash(path) File "C:Program FilesPython38libsite-packagespip_internalreqreq_uninstall.py", line 277, in stash renames(path, new_path) File "C:Program FilesPython38libsite-packagespip_internalutilsmisc.py", line 402, in renames shutil.move(old, new) File "C:Program FilesPython38libshutil.py", line 793, in move rmtree(src) File "C:Program FilesPython38libshutil.py", line 731, in rmtree return _rmtree_unsafe(path, onerror) File "C:Program FilesPython38libshutil.py", line 609, in _rmtree_unsafe onerror(os.unlink, fullname, sys.exc_info()) File "C:Program FilesPython38libshutil.py", line 607, in _rmtree_unsafe os.unlink(fullname)PermissionError: [WinError 5] 拒绝访问。: 'c:\program files\python38\lib\site-packages\pip-19.2.3.dist-info\entry_points.txt'分析了下， 应该是C:Program FilesPython38Libsite-packagespip-19.2.3.dist-info这里面出现了问题，而且应该是权限的问题， 懒得处理，
于是直接把这个文件夹删除了， 再次使用unstall命令， 得到如下结果：
直接找不到了， 于是尝试安装老版本pip
C:Usersabc>python -m pip install pip==18.0 --userLooking in indexes: https://pypi.doubanio.com/simpleCollecting pip==18.0 Downloading https://pypi.doubanio.com/packages/5f/25/e52d3f31441505a5f3af41213346e5b6c221c9e086a166f3703d2ddaf940/pip-18.0-py2.py3-none-any.whl (1.3MB) |████████████████████████████████| 1.3MB 226kB/sInstalling collected packages: pipSuccessfully installed pip-18.0WARNING: You are using pip version 18.0, however version 19.3.1 is available.You should consider upgrading via the 'python -m pip install --upgrade pip' command.安装成功， 实验pip安装
C:Usersabc>pip install xlrd --userLooking in indexes: https://pypi.doubanio.com/simpleCollecting xlrd Downloading https://pypi.doubanio.com/packages/b0/16/63576a1a001752e34bf8ea62e367997530dc553b689356b9879339cf45a4/xlrd-1.2.0-py2.py3-none-any.whl (103kB) 100% |████████████████████████████████| 112kB 937kB/sInstalling collected packages: xlrdSuccessfully installed xlrd-1.2.0You are using pip version 18.0, however version 19.3.1 is available.You should consider upgrading via the 'python -m pip install --upgrade pip' command.C:Usersabc>ok , 没什么问题