science may hold a clue - chocolate contains a substance called phenylethylamine(苯基胺), a naturally occurring chemical in the brain which promotes feelings of euphoria (愉悦)associated with being in love. it also contains a variety of other substances which may help create a feeling of well-being.do you know?

　　that same 100 grams of chocolate also contains 5 milligrams of methylxanthine and 160 milligrams of theobromine(可可碱), both caffeine-like stimulants. when taken in large quantities, these stimulants can induce nausea and vomiting-a good reason to limit your valentine`s day nibbling to a few chocolates.

　　meanwhile,chocolate is poisonous to dogs and other pets, and can even be lethal. don`t give it to your dog. theobromine is toxic to dogs, and one ounce of chocolate could kill a 10-pound canine.