物质的量浓度的意义？
参考答案：
单位体积溶液中所含溶质的物质的量即为物质的量浓度
He couldn’t _____ the terrible working conditions in the factory and decided to leave at once. [ ]
A. catch up with
B. put up with
C. keep up with
D. come up with
简述硅酸盐水泥的水化产物。
