something exchanging things with something else means that something taking one kind of thing from that something else and giving off another kind of thing to that something else
christmas is time_for_exchanging_gifts. tradeoff is exchange. parties is for_having_fun_with_other_people. christmas is not time_for_exchanging_gifts. exchanging_greetings is dialogue. exchanging_greetings is social_activity. parties is not for_having_fun_with_other_people. exchanging_greetings is not social_activity. another_way_to_say_separates_things is divides_objects. exchanging_greetings is not dialogue.