问题 选择题

 关于做匀速圆周运动物体的向心加速度方向,下列说法正确的是   

A.始终指向圆心

B.与线速度方向始终相反

C.与线速度方向始终相同

D.始终保持不变

答案

答案:A

匀速圆周运动物体的向心加速度始终指向圆心,与线速度方向时刻垂直,BCD错;

完形填空

A funny story circulated recently about Sir Arthur Conan Doyle, creator of the fictional detective Sherlock Holmes. Doyle clearly told of a time when he climbed into a   1    in Paris. Before he could    2     a word, the driver turned to him and asked, “Where can I     3     you, Mr. Doyle?”

Doyle was    4   . He asked the driver if he had ever seen him before.

“No, sir,” the driver responded. “I have    5    seen you before.” Then he    6    : “This morning’s paper had a story about you being on     7     in Marseilles. This is the taxi stand where people who return from Marseilles always arrive. Your    8    color tells me you have been on vacation. The    9     spot on your right index finger suggests to me that you are a  writer. Your clothing is very English, and not French.    10    up all those pieces of information, I    11    that you are Sir Arthur Conan Doyle.”

“This is truly amazing!” the writer   12    with excitement. “You are very like my    13    creation, Sherlock Holmes!”

“There’s one other thing,” the driver said.

“What’s that?”

“Your    14     is on the front of your suitcase.”

Perhaps the     15    was no master detective, but he was observant! He paid attention and paying attention is an important part of living    16    .

Life isn’t a matter of milestones, but of    17   . A life lived to the full is lived from moment to moment,    18    from milestone to milestone. It is more of a series of days in which we truly pay attention, than a few    19   events along the way.

Pay attention to the things of life, to people, to events, to your senses, even to the ordinary. Your life will never    20    beauty. By making the most of the moments, you make the most of the years.

1. A. train                B. taxi               C. bus             D. plane

2. A. write                 B. hear              C. say             D. read

3. A. take                  B. meet              C. wait            D. leave

4. A. pleased               B. scared            C. disappointed     D. surprised

5. A. just                  B. never              C. ever            D. always

6. A. admitted            B. started             C. explained        D. remembered

7. A. business               B. duty              C. holiday          D. work

8. A. skin                  B. hair               C. clothes          D. shoes

9. A. blood                 B. dirt               C. mud             D. ink

10. A. Making              B. Taking             C. Putting          D. Adding

11. A. concluded             B. realized            C. imagined        D. expected

12. A. sighed               B. screamed           C. whispered         D. roared

13. A. mental           B. physical            C. fictional         D. psychological

13. A. license               B. address            C. resume           D. name

15. A. driver                 B. writer             C. detective         D. waiter

16. A. well               B. fully               C. happily          D. peacefully

17. A. stages              B. steps               C. periods          D. moments

18. A. more than            B. less than            C. rather than       D. other than

19. A. small                 B. major              C. personal          D. social

20. A. lack                 B. create              C. appreciate         D. enjoy

单项选择题