Definition: You are given a conversation between two people. 'Person1:' and 'Person2:' are used to separate their respective dialogues. You are required to assign a label 'formal' if there is an absence of emotion and a presence of questions anywhere within the conversation. If such pattern is not found assign the label 'informal'.
Input:  Person1:       Do you object to drinking black tea , Mr.Zhang ?  
 Person2:Yes , that is why I never drink it .  
 Person1:        Do you drink green tea , then ?  
 Person2:Very seldom , because tea has tannin which may be harmful to one's health .  
 Person1:        But if the tea is good and well prepared , it will do much good .  
 Person2:What good is it for ?  
 Person1:        Not only can it appease one's thirst , but it can also refresh one when tired .  
 Person2:That's true , but it must not be allowed to stand long .  
 Person1:        Why is it so ?  
 Person2:Because if you drink a kind of tea which has been prepared for some time before , it will do you harm . 

formal