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.
Dialogues
A: Would you do me a favor?
你能帮我一下吗?
B: Sure. What is it?
当然可以,什么事?
A: Could you give me a ride home tonight?
今晚能送我回家吗?
B: Yeah. I guess. Don't you live kind of far away, though?
我想可以。不过,你是不是住的有点儿远?
A: Would you mind picking up some things on your way home from work?
你能在下班回来的路上给我买点东西吗?
B: Sure. As long as it doesn't take too long.
当然可以。只要不花太长时间就行。