Once the riddle was out, the room became silent again. The kids were all gaping in surprise while the teachers bit their lips hard.
'Why the riddle is so difficult, ah? Even adults like us still can't think of any answers!'
Confused, the kids started to discuss among themselves,
"Mountain without a tree, ah? Is that miniature?"
"No! It must be a 3D model…"
"Maybe a human-made mountain?? My dad made one once!"
"But it's not only mountains...a city without houses...what's that?"
"It's a newly-built city! So it's still in progress?"
"Well, it can be...my mom created a city for my birthday years ago…"
"Bah, that must be a mini-city, this one should be large!"
"Hey, hey, what about the river? There's a river but no fish inside?"
"Maybe the river is poisonous?"
"I know it must be my dad's company catching all the fish!"
