问题 单项选择题

胡萝卜、西红柿和其他一些蔬菜含有较丰富的β-胡萝卜素,β-胡萝卜素具有防止细胞癌变的作用。近年来提炼出的β-胡萝卜素被制成片剂并建议吸烟者服用,以防止吸烟引起的癌症。然而,意大利博洛尼亚大学和美国德克萨斯大学的科学家发现,经常服用β-胡萝卜素片剂的吸烟者反而比不常服用β-胡萝卜素片剂的吸烟者更易于患癌症。 以下哪项如果为真,最能够解释上述矛盾( )

A.有些β-胡萝卜素片剂含有不洁物质,其中有致癌物质

B.意大利博洛尼亚大学和美国德克萨斯大学地区的居民吸烟者中癌症患者的比例都较其他地区高

C.经常服用β-胡萝个素片剂的吸烟者有其他许多易于患癌症的不良习惯

D.吸烟者吸人体内烟雾中的尼古丁与β-胡萝卜素发生作用,生成一种比尼古丁致癌作用更强的有害物质

答案

参考答案:D

解析: A项属于特例,并不能解释普遍性的现象,C项不能说明服用β-胡萝卜素片剂的吸烟者是否比其他吸烟者有更多的不良习惯,B项与题干推理过程无关。所以答案为D。

阅读理解

阅读理解

       A 10-year-old boy decided to study Judo(柔道), although he had lost his left arm in a car accident.

He began his lessons with an old Japanese Judo teacher. He was doing well, but he could not understand why the teacher had taught him only one move for quite a long time.

       "Sir," the boy finally said, "I think I should learn more moves."

       "But this is the only move you will ever need to know," the teacher answered.

       Not quite understanding, the boy kept training. Several months later, the teacher took the boy to his

first tournament(联赛). Surprising himself, the boy easily won his first two matches. The third match

proved to be more difficult. However, after some time, the opponent(对手) became impatient. The boy

used his one move to win the match. Now the boy was in the finals.

       This time, his opponent was bigger, stronger and more experienced. Thinking that the boy might get

hurt, the referee(裁判) wanted to stop the match.

       "No," the teacher said, "let him continue."

       Soon his opponent made a mistake. Immediately the boy used his move to attack him. The boy won

the match and became the first one.

       On the way home, the boy and the teacher reviewed every move in every match. Then the boy asked what was really on his mind. "How did I win the tournament with only one move?"

       "You won for two reasons," the teacher answered. "First, you've mastered(掌握) one of the most

difficult moves in Judo. And second, the only known defense(防卫) for that move is to grasp(抓住) your

left arm. But you've lost it." The boy's biggest weakness had become his biggest advantage.

1. Why did the referee want to stop the final match?      

A. Because the boy was not ready for the final match.                    

B. Because the boy's opponent was much stronger than him.

C. Because the boy was too tired to fight in the match.

D. Because the boy's teacher asked the referee to stop it.

2. What's the correct order of the following events?

a. The boy won the final match.

b. The boy began to learn Judo.

c. The boy lost his left arm in an accident.

d. The boy won the first three matches.

e. The boy learned why he won the matches.

A. c-b-d-e-a      

B. c-b-d-a-e      

C. b-c-d-e-a      

D. b-c-d-a-e

3. The boy won the final match because of the following reasons EXCEPT ______.

A. the boy acted in a different way this time

B. his opponent couldn't grasp the boy's left arm

C. the boy pinned his opponent at the right moment

D. the boy mastered one of the most difficult moves in Judo

4. What can we learn from the passage?

A. We shouldn't look down on disabled people.

B. We can win a match if we know ourselves well.

C. Our disadvantages can be advantages sometimes.

D. Disabled people can't be successful, too.

单项选择题 共用题干题