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问题 单项选择题

用煮沸法杀死细菌繁殖体至少需要

A．30min

B．5min

C．15min

D．2min

E．1h

答案

参考答案：D

解析：大多数无芽胞细菌55～60℃加热30～60min即被杀死；加热100℃立即死亡，有芽胞的破伤风芽胞梭菌需煮沸3h才被杀死。

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     I knew little about English when I first came to America. So I went to a language school every day
to    1    English. One day, during the break, I asked one of my classmates a question. When I thanked her
for it, she said,"    2   . It's a piece of cake." I thought to     3   , "She wants a piece of cake?" So I said to
her, "I haven't taken any piece of    4    with me today. What about a piece of biscuit (饼干)?"
      She looked at me in surprise and then smiled. She knew that I didn't    5    her. She said, "What I mean
is 'no problem,'" Then I began to learn that "a piece of cake" is not only a piece of cake, but also means a
thing that is very easy.
( )1. A.tell   
( )2. A.All right         
( )3. A.yourself  
( )4. A.bread  
( )5. A.understand		B.know     
B.The same to you 
B.myself                   
B.pizza     
B.remember   		C.teach         
C.You’re welcome 
C.himself       
C.biscuit        
C.find                           		D.learn                
D.Nothing serious  
D.herself            
D.cake               
D.believe            
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单项选择题

为了设计上的便利，对于四边均有支承的板，当（）按单向板设计。

A.

B.

C.

D.
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