单选题
The discount of 9% agreed upon was granted only ______ no balance was outstanding from previous accounts.
【正确答案】
D
【答案解析】[解析] 此题考查由condition引导的条件状语从句，当后面是从句时一般都用on condition that，当然depend on也可表示条件，但depend on后面只能接名词短语，而不能引导从句。比如depend on your attitude。