"Half of the class was late" 或 "Half of the students in the class were late" 。

其中, "half" 是指一半，"class" 是指班级，"late" 是指迟到。

例句1:
"Half of the class was late for the first day of school."
（第一天上学时，一半的班级迟到了。）

例句2:
"I was surprised to see that half of the students in the class were late today."
（今天我很惊讶地发现班里有一半的学生迟到了。）

例句3:
"The teacher was not happy when half of the class was late for the exam"
（考试时一半的班级迟到，老师不高兴。）