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                                    單項(xiàng)選擇題
                                    
      1kWh電能可供“220V，40W的燈泡正常發(fā)光時(shí)間是（）h．
      
                                
      
                                
                                    
      
	A．100
      
	B．200
      
	C．95
      
	D．25
      

      
                                
                                
                                
      
                                    
                                
      
                                

                        
      
                    
                
      

                
                    
                    

            
      
            
      
                
            
      
        
      
    
      
    

      

      
    
      
        
      
            
      
                
                
      

                
      
            
      
        
      
    
      

      

      
    
      
        
        
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