I’d write about how it started, how it impacted and changed the society
        
                    
             
        
        
        
Answer: can you upload a picture of your work
        
             
        
        
        
I believe the linking verb is “will”. It’s linking the subject “the United States of America” and the predicate “be 300 years old!”
        
             
        
        
        
I believe the answer to your question would be young adults who want to stay healthy.