hid的過去式和過去分詞是什麼？

She felt sure the letter had some hidden meaning.

她確信那封信中有言外之意。

There are fears of a hidden agenda behind this new proposal.

人們擔心這一新提議的背後有不可告人的目的。

I stayed hidden; I couldn't chance coming out.

我躲了起來，不能冒險出去。

He knew the hidden drifts in that part of the river.

他對那段河道中的'暗流非常清楚。

I keep my private papers hidden.

我藏起了我的私人檔案。