Drop is related to Accident. Accident is a synonym of Condition. Condition is related to Clear. Clear is a type of Vanish. 
Reduction is related to Pro. Pro is related to Progress. Progress is related to Goal. 
Drop <--RelatedTo--> Accident <--Synonym--> Condition <--RelatedTo--> Clear --IsA--> Vanish 
Reduction <--RelatedTo--> Pro <--RelatedTo--> Progress <--RelatedTo--> Goal 