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。