I have been busy yesterday afternoon为什么要用have been busy而不用have busy

题目

I have been busy yesterday afternoon为什么要用have been busy而不用have busy
主要想问的是什么时候现在完成时里动词前要用been,也就是have been ...
例如还有 ：She has been sick since last month.

答案

busy是形容词,你想想i am busy .那been 对应的am ,好好琢磨下