这个错误是因为环境变量加载导致，你需要找到自己安装的conda的环境变量加载文件conda.sh，然后source 一把加载，最后就可以conda activate进入base环境

hange@hange-virtual-machine:~$ conda activate
usage: conda [-h] [--no-plugins] [-V] COMMAND ...
conda: error: argument COMMAND: invalid choice: 'activate' (choose from 'clean', 'compare', 'config', 'create', 'info', 'init', 'install', 'list', 'notices', 'package', 'remove', 'uninstall', 'rename', 'run', 'search', 'update', 'upgrade', 'build', 'content-trust', 'convert', 'debug', 'develop', 'doctor', 'index', 'inspect', 'metapackage', 'render', 'skeleton', 'pack', 'server', 'env', 'token', 'verify', 'repo')
hange@hange-virtual-machine:~$ cd anaconda3/etc/profile.d/
hange@hange-virtual-machine:~/anaconda3/etc/profile.d$ ls
conda.csh  conda.sh
hange@hange-virtual-machine:~/anaconda3/etc/profile.d$ source conda.sh 
hange@hange-virtual-machine:~/anaconda3/etc/profile.d$ conda activate
(base) hange@hange-virtual-machine:~/anaconda3/etc/profile.d$