题目

Pain is usually connected to a nervous system. When you put your hand too close to a hot stove, nerve cells send a warning of danger to your brain. 【1】 That, in turn, causes you to pull your hand away before any serious damage is done. Plants don’t have nerves or brains, so they can’t feel pain like you do.【2】 And since they can’t escape a potentially dangerous situation, they need other ways of fighting back.The biggest threat to a plant’s life is getting eaten. Some plants discourage plant-eaters from chewing on them by growing thorns or sharp little hairs, like a rose or a c既有外分泌腺功能又有内分泌腺功能的腺体是（ ）A. 胃腺 B. 肠腺 C. 胰腺 D. 肝脏