Hey there
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The correct answer is:
Nitrogen is a key element in the formation of B. amino acids ,which are substances necessary to living organisms. 
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Hope this helps you
        
             
        
        
        
Older animals are usually surly and ill-tempered.- That can be a sentence in itself as well as the second part. Accordingly it is unwise to attempt to pet a grown raccoon. All the semicolon is doing is combining two sentences to make them one.
        
             
        
        
        
Connotation is the emotion or idea that is associated with a word.
 
        
                    
             
        
        
        
Answer:
Because it could have been somebody very close to them.
Explanation:
 
        
                    
             
        
        
        
I would say I will definitely check reliability and safety.