题目

把含硫酸铵和硝酸铵的混合液a L分成两等份。一份加入bmol NaOH并加热，恰好把NH3全部赶出；另一份需消耗cmol BaCl2沉淀反应恰好完全，则原溶液中NO3－的浓度为（    ） A．        B．        C．         D．  答案：BIs this the reason __________ at the meeting for his carelessness in his work? [     ]A. he explainedB. what he explainedC. how he explainedD. why he explained