在英语口语中，关于上课的表达方式如下：

1. 开始上课：

"Let's start class."

"It's time for class."

"Good morning, class."

"Good afternoon, everyone."

2. 学生进入教室：

"I have to go to class."

"I'm going to class."

3. 学生起立和坐下：

"Stand up, please."

"Sit down, please."

4. 询问出勤情况：

"Who is on duty today？"

"Is everyone here？"

"Is anyone absent？"

5. 结束上课：

"That's all for today. Thank you for your attention."

"Goodbye, see you tomorrow."

这些表达可以帮助你在课堂上进行基本的交流。