I drew up a generic questionnaire to suit all candidates. Once you've created specific sections for each profession and that appear only in the visible ads that concern them .. These sections contain only two questions. A multiple choice, where candidates select specific competencies required by the client and other free-text to justify.

This means that each ad only contains two additional questions over the standard, which saves space in the database. I'm just using many fields to be able to repeat in each type of ad / profession, adjusting skills that can be selected.