题目

——Mr Zhang has been made the most popular teacher in our school this year.    ——He always has a way to make his class_______and interesting. A.lovely    B.lively   C.alive   D.loving 答案：A将一种浓度为15%的溶液30kg，配制成浓度不低于20%的同种溶液，则至少需要浓度为35%的该种溶液________kg．