KEEPING OUR TEETH HEALTHY It is very important to have healthy teeth. Good teeth helps us to chew our food. They also help us to look nice. How does a tooth go bad The decay begins in a little crack in the enamel covering of the tooth. This happens after

KEEPING OUR TEETH HEALTHY It is very important to have healthy teeth. Good teeth helps us to chew our food. They also help us to look nice. How does a tooth go bad? The decay begins in a little crack in the enamel covering of the tooth. This happens after germs and bits of food have collected there. Then the decay slowly spreads inside the tooth. Eventually, poison goes into the blood, and we may feel quite ill. How can we keep out teeth healthy? First, we ought to visit our dentist twice a year. He can fill the small holes in our teeth before they destroy the teeth. He can examine our teeth to check that they are growing in the right way. Unfortunately, many peole wait until they have toothache before they see a dentist. Secondly, we should brush our teeth with a toothbrush and fluoride toothpaste at least twice a day – once after breakfast and once before we go to bed. We can also use wooden toothpicks to clean between our teeth after a meal. Thirdly, we should eat food that is good for our teeth and our body: milk, cheese, fish, brown bread, potatoes, red rice, raw vegetables, and fresh fruit. Chocolate, sweets, biscuits and cakes are bad, especially when we eat them between meals. They are harmful because they stick to our teeth and cause decay. 1. When food and germs collect in a small crack, our teeth ________ A. become hard B. begin to decay C. send poison into the blood D. make us feel quite ill 2. A lot of people visit a dentist only when ________ A. their teeth grow properly B. they have holes in their teeth C. they have toothache D. they have brushed their teeth 3. We ought to try to clean our teeth ________ A. once a day B. at least twice a day C. between meals D. before breakfast 4. We shouldn’t eat a lot of ________ A. red rice B. fresh fruit C. fish D. chocolate 5. Sweets are harmful because they make our teeth ________ A. black B. ache C. decay D. cracked   ANIMATION The theory of the animated cartoon was introduced before the invention of the cinema by half a century. When working to create conversation pieces for Victorian shops, people discovered the principle of persistence of vision. If drawings of the stages of an action were shown in fast succession, the human eye would perceive them as a continuous movement. One of the first commercially successful devices, invented by the Belgian Joseph Plateau in 1832, was the phenakistoscope, a spinning cardboard disk that created the illusion of movement when viewed in a mirror, in 1834, William Horner invented the zoetrope, a rotating drum lined by a band of pictures. The Frenchman Émile Reynaud in 1876 adapted the principle into a form that could be projected before a theatrical audience. Reynaud became not only animation’s first entrepreneur but also the first artist to give personality and warmth to his animated characters. 26. What is the passage mainly about? 27. When was the theory of animation developed? 28. What happens to human eyes when pictures of the stages of an action were shown in fast succession? 29. What is a phenakistoscope? Do, does, did, will, Tobe- > yes, no