I cannot think of a single reason to agree with that idea.
I can't think of a single reason not to tell her.
He could not think of a single reason why they would want him dead.
If for any single reason, it means more women will take interest.
Because they've never given me a single reason not to.
Son, I can't think of a single reason to say no.
And neither could I think of a single reason not to.
He couldn't think of a single reason why her opinion should matter to him, but it did.
Indeed, there wasn't a single good reason that she should not be part of the mission.
"Can you tell me a single good reason why not?"