You don't have to do that.
你不必这么做。

用法透视
"have to"的意思是"不得不做"。

这个句型用来表示对方可以不做某事，或间接地表示感谢。

支持范例
1. If you are unwilling to tell them, you don't have to do it.
如果你不想告诉他们，就不必说。

2. You don't have to come so early.
你不必来这么早。

3. You don't have to wait for my permission.
你不必等我的允许。

会话记忆
A: Thank you so much for coming tonight. Everybody really enjoyed your performance.
非常感谢你今晚来表演，每个人都很喜欢你的节目。

B: I'm glad I could help.
我也很高兴能有所帮助。

A: Here's the check. I included a little extra for you.
这是支票。我额外加了一点给你。

B: You didn't have to do that!
你不必这么做的！

A: I know, but you deserve it.
我知道，但你得之无愧。