Sentence 1: Diane had 4 sons. 
 Sentence 3: She told them that if they got into med school, she'd buy them cars 
 Sentence 4:  They worked really hard for their finals 
 Sentence 5:  Diane had to stick to her word and bought 4 cars within 5 years 
 Given Sentence 2: He tripped and the plate crashed into his chest.