有的细节已经揭晓，但是更多细节仍是一个严守的秘密。

Some details have been released already, but many more remain a closely guarded secret.

youdao

电池直径15 - 20厘米并用水冷却，其成本是更加严守的秘密。

The cell, the cost of which is a more closely guarded secret, is 15-20cm across and is water-cooled.

youdao

关于你的出身，一定要严守秘密。

Guard carefully the secret of your birth.

youdao

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