Question

I have two more questions on the same theme.

Thank you.

1)Pay attention to (not at) your teachers' explanations.
2)You must put up your hand, if you want to ask a question to your teacher/your teacher a question . Are they both possible?
3) You mustn's shout at your classmates.
I have to dust off (is "off" necessary?) the furniture myself.

Answer 1

1. Yes, "pay attention to..."

2. You must raise your hand if you want to ask your teacher a question. (other phrasing is very awkward)

3. You can use "off" or omit it -- either will work.