Can you suffocate under a duvet?

Why does alcohol affect different people differently? What's the difference between white and brown sugar, and is the brown form healthier? Can you suffocate under a blanket? Why have only 28 days in February? Why do wind turbines have long thin blades but room fans use shorter wide blades? Does diluting alcoholic drinks affect how drunk you become? Why is some metal okay in the microwave but other metallic objects make sparks? Join Dr Chris and 567 Cape Talk's Kieno Kammies for this week's crop of questions. As they say - don't know the answer? Ask the Naked Scientists!