答应

No problem/All right/Of course/You got it/Happy to help/Whatever you want(need)/All you have to do is ask.

拒绝

That depends/I don't think I can/I'd rather not/I don't think so/Sorry, I can't/Not this time/You are asking for too much/Forget it/No way. 

A: Would you mind taking care of my plants while I'm out of town?我不在城里的这段时间，你能帮我照顾我的植物吗？

B: Whatever you need, just tell me what I need to do. 你需要我帮你做什么都行，只要告诉我该怎么做就行。

A: Hey, would you mind closing the door?嘿，你介意关上门吗？

B: Sure, no problem. 当然不，没问题。

A: Could you save my seat while I run and get some snacks?我去买点儿零食，你能帮我看着点座位吗？

B: That depends. Can you bring me back something too?那得看情况了。你能帮我也带点东西吗？