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单项选择题 Lowering the Risk of Heart Disease Like millions of other Americans, I come from a family with a history Of heart disease. My father had his first three heart attacks when he was only thirty-one.__________(46)I grew up with heart disease. It was there, but I didn't take it seriously.When I was thirty-one, my blood cholesterol (胆固醇) level was measured for the first time. It was 311 mg/dl, the doctor told me--an extremely high level that put me at a very high risk of heart disease, 'especially with my family history. He sent me to the National Institutes of Health (NIH) to be screened for participation in a clinical trial. _________(47)At NIH, physicians explained the degree of risk associated with my bloodcholesterol level and the nature of the experiment. This test involves putting a tube through a leg artery (动脉) up to the heart._________(48)Learning about the risks of the experiment as well as the risk associated with my raised blood cholesterol level scared the life out of me. Although I was excluded from participating in the study, the experience may well have saved my life.For the first time, I began to realize the seriousness of high blood cholesterol.___________(49) But equally important, I got a taste of what it is like to be a patient, to have tests done on me and to think of myself as sick. This was hard to take.This experience taught me two lifesaving lessons. First, although I felt fit and strong, I was actually at high risk for heart disease because of my high blood cholesterol level. And with my family history, it could not be ignored.___________(50) A.The death rate for the test was only 1 in 100, I was assured.B.Second, I could lower my blood cholesterol level simply by changing what I ate.C.I was three years old at that time.D.There is not enough oxygen in the blood.E. It was a heart attack just waiting to happen.F. The trial was designed to test the effect of lowering blood cholesterol on the risk of heart disease. 第 46 题 请选择(46)处的最佳答案.

单项选择题 Crystal Ear One day a friend asked my wife Jill if I wanted a hearing aid. 'He certainly does, 'replied Jill. After hearing about a remarkable new product, Jill finally got up the nerve to ask me if I'd ever thought about getting a hearing aid. 'No way,' I said. 'It would make me look 20 years older.' 'No, no,' she replied. 'This is entirely different. It's Crystal Ear!'Jill was right. Crystal Ear is different--not the old-styled body worn or over-the-ear aid, but an advanced personal sound system so small that it's like contacts (隐性眼镜) for your ears. And Crystal Ear is super-sensitive and powerful, too. You will hear sounds your ears have been missing for years. Crystal Ear will make speech louder, and the sound is pure and natural.I couldn't believe how tiny it is. It is smaller than the tip of my little finger and it's almost invisible when worn. There are no wires, no behind-the-ear device. Put it in your ear and its ready-to-wear mold (形状) fits comfortably. Since it's not too loud or too tight, you may even forget that you're wearing it! Use it at work or at play. And if your hearing problem is worse in certain situations, use Crystal Ear only when you need it.Hearing loss, which occurs typically prior to teenage years, progresses throughout one's lifetime. Although hearing loss is now the world's number one health problem, nearly 90 percent of people suffering hearing loss choose to leave the problem untreated. For many millions, treating hearing loss in a conventional way can involve numerous office visits, expensive testing and adjustments to fit your ear. Thanks to Crystal Ear, the 'sound solution' is now convenient. Almost 90 percent of people with mild hearing loss, and millions more with just a little hearing drop-off (下降), can be dramatically helped with Crystal Ear. Moreover, its superior design is energy-efficient, so batteries can last months. Crystal Ear is now available to help these people treat their hearing loss with a small hearing amplifier (放大器). 第 36 题 Initially the writer did not want to buy a hearing aid becauseA. it would make him look old.B. it would make him nervous.C. it was too expensive.D. it was old-styled.

问答题 M.Green在果蝇中发现了一个特殊的X连锁的焦刚毛(sn)基因。雌性纯合体具有焦刚毛,但在它们的头、胸、腹部有许多区域具有sn+(野生型)刚毛。该雌性纯合体果蝇与sn雄性杂交时,一些雌性亲本仅产生焦刚毛后代,而另一些雌性亲本则以可变的频率产生焦刚毛和野生型的后代。试解释之。