题目

（2010·黑龙江大庆实验中学高三第二次月考）25. There was a time in the USA when the money spent on educating a black child was just one fourth of _____ spent on each white child. A. it        B. one  C. that          D. what 答案：C组织里的气体交换是指血液与_________之间的气体交换．