题目改成under the tree在树下
1）如果是对that girl,提问的话,应该是
who is singing under the tree?
2）如果是对that提问的话,
应该是 which girl is singing under the tree?
3）如果是对singing提问的话,
应该是 what is that girl doing under the tree?
4）对 under the tree 提问的话
应该是where is that girl singing?that girl is singing under the thee 对划线部分提问issinging对划线部分提问确切的说，应该是对singing提问，如果把is也划进去，这句话没动词了。答案是：what is that girl doing under that tree？