Answer:
He gallantly strode across the gorge, not worried about the big beast coming after him. 
Fred assailed Joe. 
They were in discord with their neighbors. 
Explanation:
Gallantly means: in a brave or heroic manner.
Assailed means: To make a violent attack. 
Discord means: A lack of harmony between people, or a disagreement. 
 
        
             
        
        
        
If you're trying to write a story that "ends with the words: How wrong he was" you may want to make the story about some kind of stance you make that he disagrees with. You could choose any topic that usually creates tension between people, such as politics or the environment. 
        
             
        
        
        
Hello there! I personally believe the answer will be:
the contents of a new textbook
The other ones seemed rather informal. Weekend plans with friends have no formality at all. As do the places to shop online for new shoes. The last one could be a candidate but it seems like something you would talk about with a friend or family member. Not so much your boss! 
Hope this helped!