Alpine Expeditions operates a mountain climbing school in Colorado. Some clients pay in advance for services; others are billed after services have been performed. Advance payments are credited to an account entitled Unearned Client Revenue. Adjusting entries are performed on a monthly basis. An unadjusted trial balance dated December 31, 2011, follows. (Bear in mind that adjusting entries have already been made for the first 11 months of 2011, but not for December.)