A complex sentence can be created by adding an incomplete thought to a complete thought. It can also be created by taking two simple sentences and making one into a big sentence, which would be half a paragraph. I honestly, don't always write correctly so I use Grammerly. My whole class uses it. This sounds as if I'm advertising, but I'm not. 
 
        
                    
             
        
        
        
Answer:
u cant pay happinesss hapines is on your mouth