Drop is related to Floor. Floor is part of Hallway. Hallway is related to Stair. Stair is related to Mechanism. 
Watch is a type of Surveillance. Watch is related to Tv. Screen is part of Tv. 
Drop <--RelatedTo--> Floor --PartOf--> Hallway <--RelatedTo--> Stair <--RelatedTo--> Mechanism 
Surveillance <--IsA-- Watch <--RelatedTo--> Tv <--PartOf-- Screen 