Thank you so much.
非常感谢

Thanks a lot.
多谢

I can't thank you enough for this.
感激不尽

I don't know how I can thank you.
真不知道怎么感谢你。

I really appreciate this.
真的太感谢你了。


Dialogue1:
A: Thanks. That was really nice of you.
太感谢了，你真是太好了。

B: No problem, happy to help.
没什么，很高兴能帮到你。

Dialogue2:
A: Thanks a lot.
多谢。

B: You're welcome, I'm glad you like it.
不客气，很开心你能喜欢。

Dialogue3:
A: I don't know how I can thank you for this.
我真的不知道我该如何谢谢你。

B: That's ok. Don't mention it.
没什么的，不必再提。

Dialogue4:
A: I really appreciate this.
我真的很感谢。

B: It's nothing.
没什么的。


Conversation:
A: I really want to thank you for all of your help.
真是太感谢你提供的帮助了。

B: It was nothing, really. I'm sure you would have done the same for me.
没什么了，真的，我想你也会为我这么做的。

A: Still, you took a lot of time out of your day to help me with this presentation. You didn't have to do that.
你花了那么长时间，帮我准备这份报告，你本不必这么做的。

B: Yeah, but when I first started here, you went out of your way to make me feel welcome. I really appreciate that.
是的，但是我刚来的时候你竭尽全力让我感到很有归属感，对此我真的非常感谢。
go out of one's way表示“竭尽全力”

A: Well, I'm glad we could help each other out.
我很高兴，我们可以相互帮忙。