假定student表中有字段grade,grade代表分数,依次统计grade字段的最大值,最小值,平均值的SQL语句是
A. SELECT max(grade),min(grade),average(grade) FROM student;
B. SELECT max(grade),min(grade),avg(grade) FROM student;
C. SELECT min(grade),average(grade),max(grade) FROM student;
D. SELECT min(grade),avg(grade),max(grade) FROM student;