Mohon dibantu For centuries, people have searched for a way to replace dead and decaying teeth with comfortable false teeth. Many materials have been used to make a set of false teeth, me teeth themselves should be made from a hard and durable material. They should be secured to a soft material, making them easy to wear. In the last two decades, dentists succeeded in making durable false teeth that are comfortable too. Two thousand years ago, the Etrucans made teeth out of animal bone and gold. These materials were used-with varying degrees of success-up to the 1700's, When George Washington was president ivory form animals such as elephants became a popular material for false teeth. Doctors and inventors also tried silver, peal, and agate, but teeth made from these materials were very expensive. Perhaps the most successful material was porcelain, invented by a Frenchman about two hundred years ago. White, strong, resistant to decay, porcelain is still used today for making single teeth. Besides finding material for the teeth, inventors also had to find a way to secure them in a person's mouth. People tried wire, springs, and many kinds of glue to accomplish this. In most cases, however, discomfort and a likelihood of the teeth falling out plagued the person who wore them. Around 1844, an American dentist named Horace Wells used laughing gas to put people to sleep before working on their teeth. This innovation made dental work a lot less painful. Soon after, an inventor created the first form of rubber. This was important to dentistry because teeth could be attached to the rubber, and the rubber could be molded to fit the shape of the mouth. With these two developments, dentist could work without causing pain and could fit teeth more carefully. False teeth have become more available and comfortable since then, and dentists have continued to improve the making and use of false teeth. 1. The word varying in the second paragraph could best be replaced by the word a. Constant b. Changeless c. Fluctuating d. Stable 2. The words besides In the third paragraph means a. In addition to b. Stand next to c. Anyway d. Together 3. The word them in the third paragraph refers to a. Teeth b. Inventors c. People d. Wire 4. When was rubber found to be a useful material for false teeth? a. After laughing gas was used to put patients to sleep b. While George Washington was president c. Before a Frenchman invented porcelain d. While the Etrucans were making teeth of bone and gold 5. The word molded in the fourth paragraph means a. Formed into a shape b. To form an organic growth c. To make an ornament The fitting of a shoe Answer