I gave a reason for my absence.
Is there a reason for your strange behavior?
There is a reason why they don't want to come.
I can't give you the report for the simple reason that it isn't yet finished.
She explained her reasons for deciding to change jobs.
He wanted to know the reason for their decision.
Give me one good reason why I should believe you.
For obvious reasons, we can't do that yet.
For reasons of space, some of the charts and graphs have been omitted from the article.
She resigned for personal reasons.