"a new pair of shoes" is the object of the preposition because it answers the question 'what did Wilmer buy?"
It shows the doer of the action.It comes before verb and indicates this action or work is done by it/him/her etc.Ex.Susan switched off the lights. Who switched off the lights? The answer is Susan (subject of the sentence)
Able, sociable
ative, sedative
tion, solution
?
ic, dynamic
or, juror
Try skimming through the pages.