Be down for =be up for
想做某事；有心情做某事
in the mood for
I am not really up for going out tonight.
我今晚不想出去。

I am not really in the mood to go out tonight.
我今晚没有心情出去。
口语中可以简单说出：I am down.意思是我想去。


Be down with 好的，可以
Be ok with 好的，可以
A: Want to go grab some pizza?
吃个披萨？
B: Yeah, I am down with that.
好的，可以。

I am up for movies, but I am not down with your movie choice.
我想去看个电影。但是你选的电影我觉得不行。

We are going to the movies later tonight. Are you down?
我们今晚晚些时候准备去看个电影。想一起吗？

We are going to the movies later tonight. Are you up for it?
我们今晚晚些时候准备去看个电影。想一起吗？

Be done/through with
做完，完成，用完
I am done with my work. Let's grab a drink.
工作做完啦。我们去喝一杯。

I am done with my pen. Can I borrow yours?
我的笔用完了。能借你的吗？

Be down on sb. 批评某人
My boss is always down on me. I don't know why.

我老板总是批评我。我不知道为什么。