题干
24. When we climbed up to the top of the mountain, we were all _______.
A：tired and out of the breath
B：tiring and short of the breath
C：tired and out of breath
D：tiring and short of breath
答案(点此获取答案解析）
C
的足量硝酸中，得到的Cu(NO3)2和Mg(NO3)2溶液的浓度分别为amol·L－1和bmol· L－1（忽略溶液体积变化）。则a与b的关系为