Glad is related to Pleased. Pleased is the opposite of Cross. Cross is related to Related. Related is related to Chemistry. 
Free is a synonym of Rescue. Rescue is the opposite of Capture. Trap is a type of Capture. 
Glad <--RelatedTo--> Pleased <--Antonym--> Cross <--RelatedTo--> Related <--RelatedTo--> Chemistry 
Free <--Synonym--> Rescue <--Antonym--> Capture <--IsA-- Trap 