题目

迅速除去铝壶底的水垢，最好的试剂是(    ) A.浓盐酸           B.稀硝酸             C.浓硫酸                D.浓硝酸 答案：D  解析：第一要明确题目的意思是反应速率快且不能把铝单质反应掉，第二要知道水垢的成分是碳酸钙和氢氧化镁。 -Did you reach the US the next day??? - No. Somehow . it was three days_______ I arrived there.A. since?????????????? B.when???? ??????? C. that??????????????? D. before?