Do not open the door! There's a dog behind the door.

Do not open the door! There's a duck behind the door.

Do not open the door! There's a dragon ( 龙 )behind the door

Do not open the door! There's a deer ( 鹿 ) behind the door.

Do not open the door! There's a donkey ( 驴 ) behind the door.

Do not open the door! There's a dinosaur （恐龙） behind the door.

Do not open the door! There's a dentist （牙科医生） behind the door.

Please, do not open the door! I told you so 。

Questions: What are there behind the door?