不是因为我不愿意跟你一起去，而是因为我现在很忙。

It is not that I am unwilling to go with you, but that I'm busy now.

youdao

啊！是的，以前我很忙，但现在不太忙。(上个星期我很忙，但是现在我并不是很忙。)

Ah yeah, before I'm too busy but right now I'm not very busy. (I was busy last week but now I'm not that busy.)

youdao

并不是我不愿意跟你一起去，而是我现在很忙。

Not that I'm unwilling to go with you, but that I'm busy now.

youdao