英语课堂上常用的口语包括：

开始上课

Let's start now. / Let's begin our class / lesson.

It's time for class.

Class begins.

问候

Hello, boys and girls / children.

Good morning, class / everyone / everybody / children / boys and girls.

Good afternoon, class / everyone / everybody / children / boys and girls.

考勤

Who's on duty today？ / Who's helping this morning / today？

Is everyone / everybody here / present？

Is anyone away？ / Is anybody away？

Is anyone absent？ / Is anybody absent？

Who's absent？ / Who's away？

Where is he / she？

课堂指令

Stand up, please.

Sit down, please.

Please open your books.

Stand straight, please.

提问与请教

Can you explain this again, please？

What does this word mean？

Can you give me an example？

I don't understand this part.

Could you repeat that, please？

参与课堂活动

I think the answer is ...

Can I try？

I'm not sure, but I'll guess.

表达意见与建议

I have a different opinion.

I think this is too hard.

其他常用语

Pardon？

Again, please.

Try to be on time. / Don't be late next time.

这些口语表达在英语课堂上非常实用，有助于教师和学生进行有效的沟通和互动。