They keep that night a special secret which makes them feel even closer to each other.

那天晚上的事成了他们的秘密,这让他们觉得彼此更亲近了。

耶鲁公开课 - 心理学导论课程节选

I'm going to keep this secret like a good friend.

我会像一个好朋友那样严守秘密。

That's all实战 - SpeakingMax英语口语达人

I promised Sarah that I was going to keep it a secret.

我答应Sarah我会严守秘密的。

I can't 实战 - SpeakingMax英语口语达人