Sentence 1: Tom walked home from the library. 
 Sentence 3: He stood under a tree, trying to cover his computer bag 
 Sentence 4:  He finished the walk home after it stopped raining 
 Sentence 5:  His computer screen stopped working because it got wet 
 Option 1: It started raining before he got there. 
 Option 2: He enjoyed the sunshine the whole way home.