Helicopter is related to Blade. Blade is a type of Leaf. 
Helmet is related to Metal. Metal is related to Object. Object is related to Top. Top is related to Mountain. 
Helicopter <--RelatedTo--> Blade --IsA--> Leaf 
Helmet <--RelatedTo--> Metal <--RelatedTo--> Object <--RelatedTo--> Top <--RelatedTo--> Mountain 