There is a ball under the desk.对a ball 提问 These are balls under the desk.对balls进行提问

There is a ball under the desk.对a ball 提问 These are balls under the desk.对balls进行提问
There is a ball under the desk.对a ball 提问 These are balls under the desk.对balls进行提问

There is a ball under the desk.对a ball 提问 These are balls under the desk.对balls进行提问
What is under the desk?
What are under the desk?

what is it under the desk?
what are these under the desk?

第一个答案是：What is under the desk?;第二个答案是：What are under the desk?

What is under the desk ?
What are under the desk?