order by 碰到 union

[size=large][size=xx-large]一个学生表stu,有中学生和小学生,记录考试成绩,
现在要查出成绩最高的10名中学生和10名小学生,
怎么写sql?
select top(10) * from stu where type=中 order by score desc
union
select top(10) * from stu where type=小 order by score desc
这样会报错, 那恰当的写法是怎样的呢?
sql server环境下.
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