分身乏术 ---- One can't be in two places at once

例句：
A: Could yon come to my birthday party this weekend?
这个周末请你来参加我的生日宴会好吗？
B: Thanks. But I'm very busy with my business, so I can't be in two places at once.
多谢。但是我业务非常繁忙，因此分身乏术。

注释：
be busy 忙着做