一个圆形街心花园的周长是25.12米，这个花园的半径是______米．

阅读理解。

     What are your hobbies? Many children like stamp-collecting in their spare time. Do you know? Stamp

collecting didn't start until 1854.   As time passes,  there are more  and more  stamp-collectors.  Not only

children  but  also  men  and women are  collectors.   In some countries,  there are even lessons  on stamp

collecting in school. People are becoming more and  more interested  in stamps.  Every picture on a stamp

has its meaning in it.  It may be the head of a famous person,  an important place or special moment.  Each stamp tells us a story.   We can learn  a  lot  from stamps.   Now  stamp-collecting is my favourite hobby.  

Why not join us?          

1. Stamp-collecting started___________.

A.  earlier than 1845                

B.  later than 1921

C.  in 1854                        

D.  hundreds of years ago

2. Stamp-collectors are___________.

A. men and women                

B.  boys and girls

C.  neither young nor old          

D.  both A and B

3.  Lessons on stamp-collecting are given in___________.

A. a few countries  

B.  few countries  

C.  our country  

D.  America only

4. There are more and more stamp-collectors. This sentence means           

A. people are collecting different kinds of stamps

B. the number of stamp-collectors is growing

C. a group of people are collecting stamps

D. more and more stamps are being printed

5. Every picture on a stamp __________.

A. is the head of a stamp-collector

B. tells us something interesting

C. has nothing to do with America

D. tells us a story about some schools

一个长方体，长、宽、高分别是9厘米、7厘米和6厘米，从中截去一个最大的正方体，正方体的体积是______立方厘米．

下列哪些参数不属于HRCT扫描参数（）

A.高电压（大于120kV）

B.大矩阵（大于512×512）

C.骨算法

D.大螺距

E.薄准直

哪种死因形成口鼻腔外蕈形成泡沫（）。

A.勒死

B.缢死

C.掐死

D.溺死

E.癫痫病