英语翻译：我们知道你已经坐了无期徒刑中的20年的牢

We know you've already served 20 years for life imprisonment.

BS楼上的机器翻译

We know that she has been sitting in a life of 20 years in prison

We know that you were condemned to get a term of 20 years in prison.

汉语主动态，英语要用被动态，即“被”判刑。

We know that you've finished serving 20 years of your life imprisonment.