1. I'll tell you when you're older.

等你长大了，我再告诉你。

2. I'd rather not talk about it.

我不想谈论这件事。

3. Wait and see.

等着瞧吧!

4. No comment.

无可奉告。

5. Promise not to tell on me!

你得保证别告发我!

6. Let me get back to you.

我过会儿打给你吧。

7. I'll spare you the details.

我就不说细节了。

8. If you promise not to tell anyone else, I'll bring you in on it.

如果你答应不告诉别人，那么我就把这件事告诉你。