Question

The watch is on the sofa对划线部分提问（on the sofa)

The keys are under the chair.该一般疑问句
Are the keys in your schoolbag做否定回答

Answer 1

1 Where is the watch？
2 Are the keys under the chair？
3 No ，they aren't

Answer 2

1. on the sofa体现地点，所以借助疑问词where

   Where is the watch?

2. Are the keys under the chair?

3. No, they aren't.
   

Answer 3

Are the keys under the chair?
---No, they aren't.