Not at all.
It's a pleasure.
My pleasure.
Sure.
Don't mention it.
At your service.
I was happy to do it.
What are friends for?
you're wellcome
that's all right
it's OK!
no problem man
piece of cake!
My pleasure.
anytime.
答：今天帮老师做了件事,老师说Thank you ,但我不知道不用谢用英语怎么表达
直接说that's all right