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Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions    Just as optical fibers have transformed communication, they are also revolutionizing medicine. These ultra - thin, flexible fibers have opened a window into the living tissues of the body. By inserting optical fibers through natural openings or small incisions and then threading them along the body's established pathways, physicians can look into the lungs, intestines, heart and other areas that were formerly inaccessible to them.  The basic fiber-optics system is called fiberscope, which consists of two bundles of fibers. One, the illuminating bundle, carries light to the tissues. It is coupled to a high-intensity light source. Light enters the cores of the high-purity silicon glass and travels along the fibers. A lens at the end of the bundle collects the light and focuses it into the other bundle, the imaging bundle. Each fiber in the bundle transmits only a tiny fraction of the total image. The reconstructed image can be viewed through an eyepiece or displayed on a television screen. During the last five years, improved methods of fabricating optical fibers have led to a reduction in fiberscope diameter and an increase in the number of fibers, which in turn has increased resolution.  Optical fibers can also be used to deliver laser light. By use of laser beams, physicians can perform surgery inside the body, sometimes eliminating the need for invasive procedures in which healthy tissue must be cut through to reach the site of disease. Many of these procedures do not require anesthesia and can be performed in a physician's office. These techniques have reduced the risk and the cost of medical care.  What is the main topic of the passage?

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Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 31 to 35. Dinosaurs were reptiles that lived during a period of earth’s history called the Mesozoic Era, which is known as the Age of Reptiles. The first dinosaurs appeared more than 200 million years ago. For many millions of years, they dominated the land with their huge size and strength. Then about 65 million years ago, they died out rather suddenly, never to reemerge. The word dinosaur comes from two Greek words meaning “terrible lizard”. Dinosaurs were not lizards, but their appearance could be truly terrifying. The biggest ones weighed more than ten times as much as a mature elephant and nearly equaled the size of most modern-day whales. The famous kinds of dinosaurs, including the brontosaurus and tyrannosaurus, reached 80 to 90 feet in length. Not all dinosaurs were giants, however, some were actually no larger than a chicken. Scientists still do not know what caused dinosaurs to disappear. One theory involves a change in the earth’s climate. It is believed that temperature dropped significantly towards the end of the Cretaceous Period. Too large to hibernate and not having fur or feathers for protection, it is possible that the climate became too chilly for dinosaurs. In contrast, other species having protection, such as the mammals and birds, were able to survive.  What is the best title for this passage?

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