分级

例句：

1. 1. The students are being graded ontheir performance in the exam.
   学生们正在根据他们在考试中的表现进行评分。
2. 2. This book isdivided into different levels of difficulty for easyunderstanding.
   这本书被分成不同难度级别，以便容易理解。
3. 3. The company has implemented a tiered system to rank its employees based ontheir performance.
   该公司实施了一个分级系统，根据员工的表现来排名。