Sentence 1: I sell things online. 
 Sentence 3: I posted it on Craigslist 
 Sentence 4:  I sold the unit for $100 
 Sentence 5:  My friend bought me a beer 
 Option 1: My computer illiterate friend wanted to sell his tool cabinet. 
 Option 2: My computer illiterate friend wanted to sell his screw driver.