Sentence 1: Belle lost her keys. 
 Sentence 3: She checked her windows, but they were all locked 
 Sentence 4:  She had to call a locksmith for help 
 Sentence 5:  The locksmith let Bella into her house 
 Option 1: She arrived home from work and her boyfriend let her in. 
 Option 2: She arrived home from work but she couldn't get in.