题型:名词解释 将a%的某物质的水溶液加热蒸发掉m g水(溶质不挥发、且蒸发过程无溶质析出),所得溶液体积为V L,溶质的质量分数为蒸发前的2倍,设溶质的相对分子质量为M,则蒸发后所得溶液的物质的量浓度为( ) 查看答案
题型:名词解释 Someone called me at midnight, but he hung up _____ I could answer it. [ ]A. as B. since C. after D. before 查看答案