我猜你想知道What is there in your bag和What is in your bag的区别吧。
Notice that the difference in your interrogative clauses"What is in the box?"and"What is there in the box?"is related to the difference in their declarative versions:"X is in the box."and"There is X the box."
请注意，您的疑问句中的不同之处是``盒子里面是什么？'' 和“盒子里面有什么？” 与陈述句版本的差异有关：“ X is in the box”。 和“There is X in the box”。