Interestingly enough, in China (where the first clear impressions of feathered therapods were found), the Mandarin words for "dinosaur" and "dragon" are the same. So, in a sense, yes, there were once dragons. Some even flew, although so far as we can tell, they weren't intelligent, and none of them breathed fire.
Oh, Ubby^3, have you seen an American channel called The Discovery Channel? They had a really interesting show on last year - might be available on DVD - speculating on what real dragons might have been like. (For instance, the fire-breathing, in their story, was a defensive mechanism, developed from their aquatic ancestors' flotation bladder - full of hydrogen. The dragon would store hydrogen in the bladder, then, when attacked, belch it forth, striking sparks with its teeth. Foom!) Pretty cool show, I thought - and narrated by Patrick Stewart (Capt. Picard from Star Trek: The Next Generation, Prof. Xavier from the X-Men movies).
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Sodium is a metal that reacts explosively when exposed to water. Chlorine is a gas that'll kill you dead in moments. Together they make my fries taste good.