Sentence 1: Mary had been taking care of the baby at night for the past week. 
 Sentence 3: Her husband complained that it wasn't that hard 
 Sentence 4:  So he agreed to do it to try and prove his point 
 Sentence 5:  Mary smirked at her husband's exhausted face the next morning 
 Given Sentence 2: Although he knows that he can't swim, he still accepted the offer.