题目

The UK government claims that the economy is improving,  ut this survey suggests      . A.otherwise            B.therefore            C. moreover          D. meanwhile 答案：A 将a mol钠和a mol铝一同投入m g足量的水中，所得溶液的密度为d g·cm－3该溶液的质量分数为 [　　] A． B． C． D．