问题 单项选择题

假设CD盘片的存储容量为600MB,上面存放的数字图像能以每秒25幅画面、每幅画面为360×240×65536色的分辨率播放1小时,则CD盘片上的数字图像的压缩比大约是( )。

A) 25倍
B) 10倍
C) 50倍
D) 100倍

答案

参考答案:A

解析: 65536色是16位色,即每个像素占2个字节。现在1帧有360×240=86400个像素点,需要172800个字节的存储空间,则1秒25帧需要4320000个字节的存储空间,1小时是3600秒,需要15552000000(约15000MB)个字节的存储空间。现在,这15000MB数据存储在600MB的光盘上,其压缩比例也就不难算出:15000/600=25倍。本题答案为A)。

完形填空

Once again, science supports what your grandmother told you: A good night's sleep helps your body fight a cold.

People who averaged fewer than seven hours of sleep per   1  in the weeks before being exposed to the cold virus were nearly three times   2  likely to get sick as those who   3  eight hours or more, a new study found.

Researchers used frequent telephone   4  to track the sleep   5  of more than 150 men and women aged 21 to 55 over the course of a few weeks. Then they   6  the subjects to the virus, quarantined them for five days and kept   7  of who got sick.

  8  sleeping more, sleeping better also seemed to   9  the body fight illness: Patients who fared better on a measure   10  as 'sleep efficiency' - the percentage of time in bed that you're actually sleeping - were also   11  likely to get sick.

The results held   12  even after researchers   13  for variables such as body-mass index, age, sex, smoking and pre-existing antibodies to the   14   .

  15  your grandmother, the researchers aren't exactly sure   16  sleeping better makes you less likely to   17  a cold. But they   18   take a stab at the answer: 'Sleep disturbance influences the regulation of proinflammatory cytokines(促炎细胞因子), histamines, and other symptom mediators that are released in response to infection.' In plain English, maybe tossing and turning when you're   19  with the cold virus   20  to the symptoms that define a cold.

The researchers were based at Carnegie Mellon, the University of Pittsburgh and the University of Virginia, and the study was funded by the National Institutes of Health.

(   ) 1. A. day             B. night                C. week                       D. month

(   ) 2. A. more          B. as                    C. less                         D. same

(   ) 3. A. occurred     B. worked             C. averaged                  D. longed

(   ) 4. A. interviews   B. reports             C. announcements         D. demands

(   ) 5. A. hobbies       B. quality             C. progress                  D. habits

(   ) 6. A. exposed      B. placed              C. protected                 D. prayed

(   ) 7. A. touch          B. check                      C. track                       D. reward

(   ) 8. A. Except               B. Besides             C. Within                     D. Through

(   ) 9. A. benefit               B. guard                C. help                             D. assist

(   ) 10. A. known      B. acted                C. appointed                D. classified

(   ) 11. A. more         B. less                  C. far                          D. totally

(  ) 12. A. ideal         B. false              C. actual                     D. true

(   ) 13. A. adopted     B. adjusted            C. enlarged                  D. employed

(   ) 14. A. bodies       B. cells                 C. virus                       D. medicines

(   ) 15. A. Like          B. As                    C. Against                    D. By

(   ) 16. A. What               B. When               C. Where                     D. Why

(   ) 17. A. develop     B. form                C. fight                       D. prevent

(   ) 18. A. did           B. often                C. do                           D. never

(   ) 19. A. infected     B. surrounded       C. limited                    D. attached

(   ) 20. A. pulls         B. promotes          C. speeds                     D. contributes

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