What most naturally follows?

How to ask a professor for a paper extension
Double-check your course's policies.
Before you actually ask your professor, read over the class syllabus and any other course policies. Sometimes professors will say if they automatically grant extensions, are willing to consider them in certain circumstances, or have a no-extension policy.
Knowing what your professor's rules are, and what they're willing to do, will help you phrase your request correctly. Show evidence if you say you are sick.