Many people nowadays have to wear false teeth when they was middle-aged.

Since the beginning of this century,(1)………………decay has greatly increased. The amount(2) ………………sugar in our food has also increased Doctors and dentists now know that(3)……………………..is the chief cause of tooth(4) ……………. Eskimos’ teeth, for example, started to(5)……….when they began to eat sweet(6)……………...

Long ago doctors did not like(7)………treat people’s teeth. Barbers and blacksmiths(8)…………….after people’s teeth and pulled them(9)………… when they decayed. Some people thought(10)…………………………….was a punishment from the gods.

IV. (8Q9.13) Find mistake in each sentence and correct it. 1. What do you do if you won the first prize of the lottery? 2. Would people be able to fly if they have feathers instead of hair? 3. John now wishes he hasn’t broken his encouragement with Marian. 4. I would do it if I could, but I can’t so I wouldn’t even try. 5. If a drop of oil is placed in a glass of water, it would float on the surface. 6. If Peter had been more careful, he wouldn’t break the camera I lent him. 7. David wouldn’t have made such a lot of mistakes if he hasn’t been so tired. 8. How nice it would be for our parents if we could build the house. 9. He wouldn’t have able to pass the test if his English hadn’t been good enough. 10. If only we knew all this information about the market many weeks ago. V. (A8Q11.12) Choose the correct word to complete the sentences. 1. Don’t use ______ chemicals. They are harmful to our health. (to poison/ poison/ poisonous) 2. Water pollution has ______ the river. Nobody swim here. (contaminate/ contaminated/ contamination) 3. Water pollution causes the ______ of a lot of fish. (death/ to die/ dead) 4. Water pollution causes a lot of fish to______. (death/ die/ dead) 5. The acid rain has caused great (death/ to die/ dead) to the environment. (to damage/ damaged/ damage) 6. The polluted air ______ our health badly. (to damage/ damages/ damage) 7. The serious ______ has left the river with very few fish. (contaminate/ contaminated/ contamination) VI. (A8Q11.13) Give the correct form of the words given to complete the sentences. 1. Are all type of pollution ________ to the health of humans and animals? HARM 2. The __________ are concerned about the oil spills in East Sea. ENVIRONMENT 3. Dumping ____________ waste into the lakes and rivers has caused serious water pollution. INDUSTRY 4. Many people in this area have cholera because they drink ________ water. TREAT 5. Examples of primary __________ are exhaust fume from cars, ash from volcanic eruption. POLLUTION 6. If we use water ____________ more people will have fresh water. CARE 7. The polluted water results in the _____________ of many aquatic animals and plants. DIE 8. Too much carbon dioxide in the atmosphere causes global _________. WARM 9. The reduction in air pollution was ____________ last year. DRAMA 10. The road in front of my office is always _________ when it rains heavily. FLOOD VII. (A8Q11.30) Complete the second sentence so that it has a similar meaning to the first. 1. Climbing without a safety rope is forbidden. -> You aren’t..................................................................................................................................... 2. Mary hasn’t got a satellite TV, so he can’t watch the game. -> If .................................................................................................................................................. 3. Walking home alone is not a good idea. -> You ............................................................................................................................................... 4. Throw a stone into water and it sinks. -> If .................................................................................................................................................. 5. You can’t travel on this train, if you don’t have a reservation. Unless........................................................................................................................................... 6. “If I were you, I would take the job”, said Sue. -> Sue ................................................................................................................................................ 7. The exam question was so easy that we all got it right. -> It was ............................................................................................................................................ 8. Although he wasn’t experienced, he got the job. -> Despite.......................................................................................................................................... 9. Since you haven’t finished your homework, you can’t come with them. -> If ...................................................................................................................................................