Should I leave a secondary question blank or write not applicable?

Feb 2, 2015
This is probably a dumb question but when a secondary application asks something that doesn't apply to me or I have nothing to write (ex: "if you took a year off school, explain" or "is there anything else you'd like us to know"), should i just leave it blank or write "Not Applicable"? I know I'm overthinking but what did you guys do? Thanks so much :)