In the main the secret died with him. But it was revealed in many writings in his big box.

从主要之处看，秘密随他死去了，但它在他的大盒子中的很多文稿中被披露出来了。

youdao

Who knows the secret of the black box?

黑匣子之秘密，谁人知晓？

youdao

At the same time, he could box to show everyone the things, the secret is one of them.

同时，他也可以向每一个人展示盒子内的东西，秘密就是其中之一。

youdao

Once they have voted, they tend to say, wait a minute, this is the secret ballot box and I'm not going to tell you how I actually voted.

NPR: As Election Day Nears, Poll Data Questioned

While guns, girls and gadgets have remained immutable to the world of the secret agent, instant box office success has sometimes been elusive.

BBC: The many faces of Bond

The difficulty of opening a box goes up as the number increases of secret sliding panels.

FORBES: Japanese Secret Boxes: The Coolest Security Puzzles for Kids and Adults