When I entered the room,I found her ___ (write) something.

问题描述:

When I entered the room,I found her ___ (write) something.
时态填空,请写出原因谢谢!

writing
find sb.doing sth表示发现某人正在做某事
这里表示的是我一进门的瞬间发现她当时的动作是在写什么东西