Question

I brought the book-------an auction (by preposition)

Answer 1

hey mate
ur answering is by

Answer 2

I brought the book by an auction and it is right answer. Therefore the student can follow this r answer when they come to collect answer for this question:

here BY is preposition which is used to complete the sentence and get meaning full ideas among them. Hope the it is right and follow by the student when they want to collect the best answer.