Teacher Li, I can't use these scissors.

So how can you say it politely?

Hmm... Could you help me, please?

Very good! Saying it this way makes others happy to help you.

Thank you for helping me cut the paper.

You're welcome. You can also say, 'Thank you so much!'

Oh, I understand. If I want to borrow a pen, can I say, 'Please lend me a pen'?

Yes, and you can add 'please' or 'could you' to make it even more polite.

Please lend me a pen, could you?

Very good, you've learned how to make polite requests.