[译] 我们是1997级的学生。
[误] We are students of the 1997 grade.

[正] We are students of the 1997 enrollment.
[注] 一年级、二年级的“级”须用 grade, 如:She is a student in the second grade. 她是二年级的学生。所谓 1991 级、1992 级的级指该年份注册入学者, 所以用 enrollment 为妥。