class of a lattice group

例句：

1. 1. The teacher is giving a class on the history of China.
   老师正在给学生们上中国历史的课。
2. 2. She is a member of the senior class.
   她是一名高年级学生。
3. 3. The students in the first class are doing well in their studies.
   第一班的学生在学业上表现得很好。