COMB in N-COUNT
（美国英语用法，用于first, second等词后构成名词）表示“…年级学生”
-grader combines with words such as 'first' and 'second' to form nouns which refer to a child or young person who is in a particular grade in the American education system.
例句
...a sixth-grader at the Latta School.
拉塔学校的六年级学生