2. 外语
  3. The bypass operation (心脏搭桥手术)【C1】______ open-heart surgery in which the physician takes a vein from the patient’s leg and【C2】___

The bypass operation (心脏搭桥手术)【C1】______ open-heart surgery in which the physician takes a vein from the patient’s leg and【C2】___

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问题      The bypass operation (心脏搭桥手术)【C1】______ open-heart surgery in which the physician takes a vein from the patient’s leg and【C2】______ it near the heart to construct a【C3】______ around the blockage in a clogged artery【C4】______ blood can flow freely by. The operation is performed【C5】______ about 100,000 persons a year in the U.S. and costs【C6】______ $10,000. The procedure is
designed to relieve the pain of angina pectoris (心绞痛)which occurs when the blood supply is【C7】______  and also to【C8】______ the patient more freedom of sustained activity.
     In those with advanced heart disease and blockage in several arteries, the bypass operation is considered by most doctors 【C9】______ the 【C10】______ means of prolonging life. 【C11】______   those with a less advanced disease, or when only one artery is involved, the advisability of the procedure is【C12】______ more controversial. The operation doesn’t cure the disease that caused the blocked artery【C13】______ the first place. According to some studies,【C14】______ around half of the patients who have had the bypass to relieve one artery will have another blocked artery within five years and in some cases even within one year.
     There is of course a【C15】______ rate in any major operation, which【C16】______ from physician to physician and hospital to hospital. The threat to the patient is greatly increased if he is【C17】______ generally poor condition, very advanced in age, or suffering from some serious or debilitating illness. It is essential that the operation【C18】______ by a skilled surgeon knowledgeable【C19】______ this particular technique and in a hospital with the best possible【C20】______  for his use.
【C18】
选项 A、is performed
B、performed
C、be performed
D、perform
答案C
解析 考查虚拟形式。在it is essential that．．．后面的从句中，谓语动词为should+动词原形或是直接跟动词原形。虽然perform也是动词原形，但其语态在这里不符，所以 be performed为最佳选项。
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