问题 选择题

当身体某一部分受到病菌感染发炎时,血液中明显增多的是(  )

A.血小板

B.白细胞

C.红细胞

D.水

答案

A、血小板具有凝血和止血重要作用,不具有防御功能,故不符合题意;

   B、白细胞又叫白血球,它能够吞噬血液中的细菌,保护人体不受细菌的侵害,当人体有炎症时,数量会大量增多来吞噬血液中的细菌,故符合题意.

   C、红细胞的主要功能是运输氧气和二氧化碳,这两项功能都是通过红细胞中的血红蛋白来实现的,数目一般比较稳定,故不符合题意;

  D、水是血浆的主要成分之一,身体某一部分受到病菌感染发炎时,体内的水不会发生变化,故不符合题意;

故选:B

阅读理解

阅读短文,回答问题。

         Jason Queally is one of the fastest men in the world on bicycle. But do you really call the thing in the

picture a bicycle? Well, yes, Jason's human-powered machine, With its two wheels, is, of course, a bicycle.

         Every year, a very important humanpowered bicycle is held in Nevada, USA.  The speed of a bike is

measured (测定) for only 200-metres, but players take more than a kilometre to get their bikes going fast. Jason

Queally's fastest speed for the 200metre race was 103.5 kilometres an hour.

         At this year's race, Jason failed to reach the finishing line. He was speeding along at about 70 kilometres

an hour when he began to lose control of his bike. When he tried to slow down, it began to smoke.Soon the

inside of his bike was filled with smoke.He couldn't see, and he couldn't breathe. At 70 kilometres an hour, a

crash could be very serious. Jason was frightened, but he managed to stop the bike safely. He would rapair his

bicycle and try again another time to be the world's fastest man on a bike. Better luck next time, Jason. 

         Maybe you're surprised that these bikes go so quickly, but is it useful? It could be. Cars are becoming

more and more popular, and they are very safe, comfortable and easy to drive, but they also pollute the air in

our cities. Scientists and engineers are learning from fast racing bikes how to make human-powered vehicles

that might be uesful for daily travel.

1. Is Jason's human-powered machine a bicycle?

                                                                                      

2. How often is the human-powered bicycle race held in Nevada?

   ________________________________________________________________

3. Did Jason stop his bike safely or was he badly hurt?

    ________________________________________________________________

4. Why did he lose this year's race? 

                                                            

5. What is the best vehicle for daily travel like according to the writer?

    ________________________________________________________________

问答题 案例分析题