What should I say if the professor says they are too busy?

Thank them in one line and use the exit you already wrote: say what you will do instead, such as asking the writing centre or bringing two questions to office hours. Do not renegotiate the deadline in the same email, and do not ask again that week. A refusal about timing is not a judgement about your work, and treating it as one is what turns a small request into a difficult relationship. If timing was the problem, the next request should come earlier, with a smaller ask.

Asking a Professor for Feedback on a Draft in English →