I'm having a hard time seeing how nouns become the object for a verb and sometimes how they aren't.
For example, some objectless clauses (From
http://dictionary.reference.com/search?r=8&q=verged ):
a statesman who verged on greatness - Here, greatness is a noun and the verb 'verged' is acting on it.
a situation that verged on disaster. - Here, disaster is a noun and the verb is doing the same thing.
However, according to
In "We listened to the radio", the radio is the object of the preposition to, and the prepositional object of the verb listened.
Now, in the clauses from the dictionary, there is the preposition 'on' and the nouns 'greatness' and 'disaster'. What I don't get is how 'on greatness' and 'on disaster' aren't objects.