Quand
Quel, Quelle, Quoi

When to use Quel in a french questions (French for Dummies)

Quand es-tu parti? (When did you leave?)

http://www.dummies.com/how-to/content/ten-nutrients-that-shrink-your-belly.pageCd-storyboard,pageNum-5.html#slideshow
http://www.dummies.com/how-to/content/belly-fat-diet-for-dummies-cheat-sheet.html

Questions
Elements of Grammar