Garlic and onions contain chemicals damaging red blood cells in cats and dogs. Affected red blood cells can damage or lose their ability to carry oxygen effectively. Cooking these foods does not reduce their potential toxicity. Fresh, cooked, and/or powdered garlic and/or onions are commonly found in baby food, which is sometimes given to animals when they are sick, so be sure to read food labels carefully. Many cases of human food toxicity in pets are accidental. A pet may find and chew on a package of gum or candy, or steal food from a countertop (灶台) or table. The best way to prevent this is to keep all food items in closed cupboard or areas inaccessible to pets. This may be particularly difficult during the holiday season, when more candy, chocolate, fruit baskets, and other food items are around. During these times, increased alertness (警惕性) can help prevent pets finding and eating dangerous foods.

　　Children should also be taught to never give candy, gum, or other human foods to pets.

9. What can we learn from the first two paragraphs?

　A. You can give pets human food with the recommendation of veterinarians.

　B. All human foods are deadly to pets.

　C. It is useless to turn to veterinarians after your pets have eaten dangerous food.

　D. It is easy to judge whether a pet has eaten dangerous food.

10. What effect do chocolate and grapes have in common if eaten by pets?

　A. They both can cause pets' sudden kidney failure.

　B. They both contain different amounts of theobromine and caffeine.

　C. They both can cause pets to vomit.

　D. They both can cause pets' hearts to beat irregularly.

11. What is the purpose of the author's writing this article?

　A. To tell children never to give candy, gum, or other human food to pets.

　B. To warn us not to give pets human foods as we like.

C. To tell us some human foods which are dangerous to pets.