have class只表示”上课“这个概念时class前面不用修饰语，用have classes；当表示上一堂什么（英语/汉语/数学/物理）课时要用冠词。例句：We have different classes every day。我们每天都有不同的课。

have classes例句

It's time for us to have classes.

是我们上课的时间了。

Have classes together with the Chinese students.

跟中国学生一起上课。

It's time to have classes.

是上课时间了。

We have classes in one room.

当然，我们也可以说。

The teaching building is in the east and we have classes there every day.

教学楼在东边，我们每天都有课。