If the GitHub repo has seen new commits pushed to it, while you were working locally, I would advice for:

git pull --rebase
git push

The full syntax is:  用这个命令解决

git pull --rebase origin master         
git push origin master

That way, you would replay (the --rebase part) your local commits on top of the newly updated origin/master (or origin/yourBranch: git pull origin yourBranch).