问题 单项选择题

某70岁女患者因尿路感染于5天前开始服用氨苄青霉素。现出现腹泻。取便标本,培养出大量革兰阳性葡萄球菌。试问腹泻发生机制是

A.菌群失调

B.肠毒素使腺苷环化酶活性增加

C.细菌侵袭肠黏膜所致

D.内毒素作用于肠黏膜

E.肠蠕动加快

答案

参考答案:A

完形填空
完形填空。
       We know that trees are useful in our everyday life. They     1    us many things, such as wood, rubber,
medicine and many other things. They can     2     tell us a lot about our climate (气候). If you     3     a tree,
you can see that it has many rings (年轮). Most trees get a new ring     4    year. Because of this reason, we
know     5     a tree is. A tree over a hundred years old means that it has more than a hundred     6    . When
the climate is dry or very cold, the trees do not grow very much and their rings are usually     7    . When it is
wet and warm, the rings are much thicker. If the rings are suddenly (突然地) very thin or very thick, this
means that the     8     changed suddenly. If we look at the rings on this tree, we can learn     9     the climate
for a hundred years. And we can see    10    our climate is changing today.
( )1. A. tell    
( )2. A. not     
( )3. A. cut down
( )4. A. many    
( )5. A. how big 
( )6. A. trees   
( )7. A. big     
( )8. A. climate 
( )9. A. about   
( )10. A. when    
B. ask      
B. too       
B. climb up  
B. every      
B. how long   
B. leaves    
B. thin       
B. trees     
B. to        
B. where    
C. offer       
C. to            
C. walk past  
C. the first     
C. how old       
C. people      
C. large         
C. things      
C. with         
C. how       
D. get      
D. also         
D. look at    
D. from     
D. how much     
D. rings     
D. thick                    
D. animal    
D. in         
D. while   
单项选择题