阅读下列短文,从每小题所给的A、B、C三个选项中选出一个最佳选项。
People don't mind if you put your elbows or arms on the table when you are not eating. But once you have started eating, you should only rest your forearms(前臂) on the table. You should let your kids know that table manners are more than about proper eating. Teaching your kids the following table manners whether they are eating in a restaurant or at home:
◆You should use a fork unless the food is meant to be eaten with fingers.
◆You should not fill your mouth with food.
◆You should chew with your mouth closed. Nobody likes to see food being chewed up or hear it being chewed on. You should not talk while your mouths full of food.
◆If you want something that is out of your reach, then just ask someone to pass it on to you.
◆You should not pick anything out of your teeth. If something is troubling you very much, you can excuse yourself and go to the restroom to pick it out.
◆You should always use a napkin to wipe your mouth, which should be placed on your lap when you are not using it. You shouldn't wipe your face or your nose with a napkin, both are unpleasant.
◆If you are eating at someone's home, don't forget to express(表达) your thanks to the host. Also, tell him how delicious the food is, even if it isn't.
产物不稳定，受热即脱水而生成不饱和醛． 