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【简答题】

阅读理解。
I'm a skeptic (怀疑论者) when it comes to the benefits of taking vitamins and other supplements. We
swallow far more than any other country- yet we're not the healthiest folks by far, nor do we live the longest.
There's more bad news for vitamins this week: Turns out that taking folic acid (叶酸) and vitamin B12
supplements doesn't pr heart attacks or death, according to a major new study in the Journal of the
American Medical Association. It was hoped they would, since the vitamins do reduce levels of homocysteine (高半胱氨酸), an amino acid (氨基酸) that is higher in the blood of people who have a higher risk of heart
disease. In fact, homocysteine was reduced 30 percent after one year of treatment in the participants who
took both vitamins. But in the following three years, just as many vitamin takers died as those who didn't take
the vitamins. Even worse, the study was stopped early because another similar study suggested that there may
be an increased risk of cancer from taking B vitamins.
I had been taking a health-food store monster multivitamin (综合维生素剂) for months. Coincidentally, I
had been experiencing some strange numbness in my legs that was starting to scare me. I remember sitting in
a long meeting with my ankles crossed, and when I tried to stand up I crumpled on the floor and hit my chin
on the glass coffee table because my leg had gone completely numb and worthless. As I sat there and shook
my leg, I got that'pins and needles' feeling and soon was OK. But it scared me enough to make an appointment with a neurologist, who suggested an MRI to rule out stroke, or a brain tumor(肿).
While I'll never know for sure if the vitamins caused my problem, many, many studies have reminded us
that pill forms of vitamins and minerals don't provide the same benefit as getting them from food. There's a lot
we don't know about how the human body works. Until we know more, I'm getting most of my vitamins from
the farmer's market.
1. What can we know from the last paragraph?
A. The writer is getting most of pill forms of vitamins from the markets.
B. The writer continues to take vitamins in great quantities.
C. The writer is getting vitamins from food, which can provide more benefits.
D. The writer will never take pill forms of vitamins and minerals.
2. Why do people take folic acid and vitamin B12 supplements?
A. They want to stop heart attacks or live longer.
B. They want to live longer.
C. They want to increase risk of cancer.
D. They want to experience some strange numbness.
3. Which of the following is not true according to the passage?
A. It was the multivitamin he took that caused the writer to get the 'pins and needles' feeling.
B. Taking more vitamins will not make a man healthier or live longer.
C. The vitamins can reduce levels of homocysteine in our body.
D. The less homocysteine in our blood, the less chance we'll have heart attacks.
4. The best title of the passage can be ______.
A. Vitamins: Benefit Us a Lot
B. Vitamins: No Help for Your Heart
C. Vitamins: Bad for the Brain, Too
D. Some Bad News About Vitamins.

参考答案:
参考解析:
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刷刷题刷刷变学霸
举一反三

【单选题】丝氨酸、甘氨酸和半胱氨酸的前体是( )。

A.
草酰乙酸
B.
a-酮戊二酸
C.
丙酮酸
D.
甘油酸磷酸

【多选题】半胱氨酸

A.
可生成牛磺酸
B.
可产生活性硫酸根
C.
可参与甲硫氨酸循环
D.
是生糖兼生酮氨基酸

【多选题】以下属于乙酰半胱氨酸适应症的是()

A.
浓稠痰液过多的急、慢性支气管炎急性发作
B.
对乙酰氨基酚中毒的解救
C.
环磷酰胺引起的出血性膀胱炎的治疗
D.
痛风急性发作
E.
骨质疏松症

【单选题】半胱氨酸

A.
酸性基
B.
碱性基
C.
芳香基
D.
含硫基
下列氨基酸侧链分别属上述何种基团?

【单选题】半胱氨酸R侧链有

A.
氨基
B.
胍基
C.
羟基
D.
巯基
E.
羧基

【单选题】乙酰半胱氨酸为

A.
止咳药
B.
抗酸药
C.
胃动力药
D.
平喘药
E.
祛痰药