1/ Does the boy hear a sound?
Yes, the boy hears a sound.
What does he do?
He looks up.
What does the boy hear?
The boy hears a sound.
Who hears a sound?
The boy hears a sound.
Does he see an airplane?
Yes, he sees an airplane.
Who looks up?
The boy looks up.
What does he see?
He sees an airplane.
Who sees an airplane?
The boy sees an airplane.
Does he look up?
Yes, he looks up.