do sb a favor
ask sb for help/a favor
Could you do me a favor?
Would you mind doing me a favor?
Would you mind helping me out?
Could I ask you for a favor?
Do you mind if I ask you for a favor?
Would you mind if I asked you for a favor?
I need to ask you for a favor.
I need to ask you to do me a favor.
I need to ask you for help.
A: Would you do me a favor?
B: Sure. What is it?
A: Could you give me a ride home tonight?
B: Yeah. I guess. Don't you live kind of far away, though?
A: Would you mind picking up some things on your way home from work?
B: Sure. As long as it doesn't take too long.