Secretary is a type of Assistant. Secretary is the opposite of Boss. you are likely to find Boss in/at/on Desk. 
Channel is a type of Transmission. Transmission is a synonym of Infection. Infection is a type of Disease. Disease is related to Epidemic. 
Assistant <--IsA-- Secretary <--Antonym--> Boss --AtLocation--> Desk 
Channel --IsA--> Transmission <--Synonym--> Infection --IsA--> Disease <--RelatedTo--> Epidemic 