Go ahead,please.

3個問題都要看後面是怎麼問的,肯定与否定就不同.但主要有下面的回答方式OK.
sure, go ahead.
All right.
Thanks.
Why, not at all.
Go ahead.
No.
Oh,would you? Thanks
No, don't bother, I can do it myself.
No, it's all right. I can manage.
Thanks a lot, but I am OK.