College Block (P) rented property to ARCO (D) for a gas station. The term of the lease was 20 years, and the rent was at least $1000 per month but otherwise determined by a percentage of gasoline delivered. About three years prior to the expiration of the lease, D stopped pumping gas and paid P the minimum rent due. P sued for damages contending that D should be made to pay additional sums because a covenant of continued operations was implied into the lease.