I'm wondering what______（happen）to the little girl.She looks so sad at the moment?

I'm wondering what______（happen）to the little girl.She looks so sad at the moment?
I'm wondering what______（happen）to the little girl.She looks so sad at the moment?

I'm wondering what______（happen）to the little girl.She looks so sad at the moment?
happened
一般过去时

has happened

happened，唉，回答过于简洁不给提交什么玩意儿啊