题目内容：
Lowering the Risk of Heart DiseaseLike millions of other Americans, I come from a family with a histotry of the 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 seriouly.
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 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 blood cholesterol 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 sa 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 histaory, it could not be ignored.________________（50）
A．Second, I could lower my blood cholesterol level simply by changing what I ate.
B．I was three years old at that time.
C．There is not enough oxygen in the blood.
D．It was a heart attack just waiting to happen
E．The trial was designed to test the effect of lowering blood cholesterol on the risk of heart disease.
F．The death rate for the test was only 1 in 100, I was assured.
请选择（46）处的最佳答案．
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