A、Kids are not allowed to eat snow in winter. B、Drinking alcohol is not a good way to keep warm. C、Adults like eating snow just

(19)Freezing weather can mean frostbite and low body temperature unless a person is prepared. To avoid cold-related injuries, here is a simple way to remember four basic steps to stay warm. Think of COLD— C. O. L. D. The C stands for cover. Wear a hat and scarf to keep heat from escaping through the head, neck and ears.(20)And wear mittens instead of gloves. In gloves, the fingers are separated, so the hands may not stay as warm. The O stands for overexertion. Avoid activities that will make you sweaty. Wet clothes and cold weather are a bad mix. L is for layers. Wearing loose, lightweight clothes, one layer on top of another, is better than wearing a single heavy layer of clothing. Also, make sure outerwear is made of material that is water resistant and tightly knit. Can you guess what the D in COLD stands for? D is for dry. In other words, stay as dry as possible. Pay attention to the places where snow can enter, like the tops of boots, the necks of coats and the wrist areas of mittens.(21)And here are two other things to keep in mind, one for children and the other for adults. Eating snow might be fun but it lowers the body’s temperature.(21)And drinking alcohol might make a person feel warm, but what it really does is weaken the body’s ability to hold heat.
19. What does the passage mainly talk about?
20. Why does the speaker advise to wear mittens instead of gloves in winter?
21. What can be inferred from the passage?