问题 单项选择题

  美国圣母大学尼尔·卡松教授领导的粒子物理研究小组与美国布鲁克海文国家实验室及其他5所大学的科学家,利用γ介子轰击液氢,找到了一种理论上早已预言的奇异分子存在的证据。

  现代物理学理论认为,介子与质子、中子等基本粒子一样也是由夸克所组成,但又不同于质子和中子这类由3个夸克所构成的胶子。普通介子则由一正一反的2个夸克构成。介子种类较多,但因其寿命很短,性质也不稳定,在人们日常生活中不存在。尽管理论物理界早在20世纪70年代末期预言介子还有一种新的形态――奇异介子存在,但在近20年来科学家仍未能捕捉到这种新粒子的蛛丝马迹。

  寻觅奇异介子的实验始于1989年,曾获得了美国国家科学基金和能源部的大力支持。借助于布鲁克海文国家实验室的大型粒子加速器,通过对粒子碰撞后残余物的分析,研究人员终于确信,介子家族还存在一种从未见过的新成员,该介子由一对正反夸克和胶子组成,它便是理论中预言已久的奇异介子。

  尼尔·卡松教授认为,新发现对于深刻认识和理解基本粒子之间的相互作用力意义重大,如果该研究成果获得进一步证实,则有关奇异介子的研究将有可能揭示出夸克构成宇宙万物的细节。奇异介子的发现引起美国物理学界的极大关注,美国橡胶岭国家实验室的理论物理学家特德·巴恩斯博士对该研究成果给予高度评价。

  (选自《新华文摘》1997年11期)

关于介子的论述,不正确的一项是()。

A.介子与质子、中子一样,都属于基本粒子

B.介子与质子、中子都是由夸克所组成

C.构成介子、质子和中子的夸克都是一正一反

D.介子寿命很短,在日常生活中并不存在

答案

参考答案:B

选择题
阅读理解

阅读理解。

     The 2008 National Teacher of the Year gave its prize to Michael Geisen, an American science teacher,

who is thirty-five years old and a forester (护林员). But he decided he would rather work with growing

minds than with growing trees.

     Seven years ago, Michael Geisen got master's degree in teaching and a job at a middle school. He brought

new energy to the science department there. He created school projects, and got parents' support in their

children's work. He always tried to be creative with each activity, and he didn't like using textbooks much.

One girl in his class said he could probably make it interesting to watch grass grow. During lunch, his students

come to his room to talk; get help, visit his turtle (海龟) and sometimes join him in playing the guitar. He

writes songs and develops games about science. He says one of his goals as a teacher is to create people who

will continue to learn throughout their lives.

     The National Teacher of the Year is a professional award (奖) in the United States. The program began in

1952. Each state chooses one teacher as the winner of the state teachers of the year. President George Bush

honored top teachers at the White House. He said that in Michael Geisen's first two years as head of the school

science department, students of his school got high scores on a state science test, and they were still improving.

     At the White House, Michael Geisen said that students are born to be creative, curious and alive, so we need

to really encourage students' creativity and their desire to learn useful skills to face the future world. Our job is

to educate the entire child.

1. From the text, we learn that Michael Geisen _____.

A. is an American writer.

B. has won the National Teacher of the Year twice.

C. wins support from the parents of his students.

D. got a master's degree when he was35.

2. The students of Michael Grisen think that their teacher is _____.

A. serious.

B. friendly.

C. strict.

D. rude

3. Which of the following is TRUE about the National Teacher of the Year program?

A. President George Bush started this program.

B. Each US state will decide one teacher every year.

C. It has been held worldwide each year since 2001.

D. The winners will have a chance to work at the White House.

4. From the passage we know that ______.

A. Michael Geisen won high scores in a state science test.

B. Michael Geisen is a famous scientist.

C. George Bush met Michael Geisen's students at the White House.

D. Michael Grisen is the head of the science department at his school.