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问题 单项选择题

碳氢元素测定中，氧化铜应置于（）

A、第一节电炉

B、第二节电炉

C、第三节电炉

D、以上均不是

答案

参考答案：B

阅读理解
阅读理解
Dad: Mr Green            
Age: 45                  
Date of Birth: July lOth  
Son: Jack                
Age: 13                  
Date of Birth: Oct.2nd                     		Mom: Mrs Green                    
Age: 41                          
Date of Birth: August 23rd        
Daughter: Rose                    
Age: 10                          
Date of Birth: Jan.1Oth                                           
( )1. Mrs Green is the oldest(最大的)in the family.    
( )2. Mr Green's birthday is August23rd.              
( )3. There are four people in this family.         
( )4. Jack's father is forty-five years old.            
( )5. Rose is Jack's sister.            
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选择题
如图表示一交流电的电流随时间而变化的图象，此交变电流的有效值是（　　）

A．5A

B．5A

C．3.5A

D．3.5A
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