Read the following passage and choose the best answer for each of the questions. Aging is the process of growing old. It occurs eventually in every living thing provided, of course, that an illness or accident does not kill it prematurely. The most familiar outward signs of aging may be seen in old people, such as the graying of the hair and the wrinkling of the skin. Signs of aging in a pet dog or cat include lass of playfulness and energy, a decline in hearing and eyesight, or even a slight graying of the coat. Plants age too, but the signs are much harder to detect. Most body parts grow bigger and stronger, and function more efficiently during childhood. They reach their peak at the time of maturity, or early adulthood. After that, they begin to decline. Bones, for example, gradually become lighter and more brittle. In the aged, the joints between the bones also become rigid and more inflexible. This can make moving very painful. All the major organs of the body show signs of aging. The brain , for example, works less efficiently, and even gets smaller in size. Thinking processes of all sorts are slowed down. Old people often have trouble in remembering recent events. One of the most serious changes of old age occurs in the arteries, the blood vessels that lead from the heart. They become thickened and constricted, allowing less blood to flow the rest of body. This condition accounts, directly or indirectly, for many of the diseases of the aged. It may, for example, result in heart attack. Aging is not a uniform process. Different parts of the body wear out at different rates. There are great differences among people in their rate of aging. Even the cells of the body differ in the way they age. The majority of cells are capable of reproducing themselves may times during the course of a lifetime. Nerve cells and muscle fibers can never be replace once they wear out. Gerontologists- scientists who study the process of aging- believe this wearing out of the body is controlled by a built- in biological time clock. They are trying to discover how this clock works so that they can slow down the process. This could give man a longer life and a great number of productive years. 1. What does the word “it” in line 2 refer to? A. aging B. a living thing C. an illness D. an accident 2. All the followings may be the outward signs of aging EXCEPT ­________. A. the graying of the hair B. the wrinkling of the skin C. the decline in hearing and eyesight. D. the loss of appetite 3. When does the human body begin to lose vigor and the ability to function efficiency? A. Soon after reaching adulthood B. During childhood C. Early adulthood D. Past middle age 4. What happens to memorization when the brain begins to age? A. It works less B. It becomes forgetful C. It declines D. It slows down 5. According to the passage, which of the following is NOT true? A. All living things grow old. B. Aging is unavoidable in any livings things. C. Plants show less signs of aging than any other living things. D. Most body parts wear out during the courses of a lifetime.