Hank rented a new ground-floor condominium for four months before the owner offered to sell it to him. Hank accepted the offer. After Hank became the owner, he built a small patio o the living room. At a house-warming party, one of his friends caught the heel of her shoe between some patio bricks and fell, breaking her arm. It took an abnormally long time to heal because she suffered from an unusual bone disease. What was Hank's liability in this case? Can his friend sue him?