Use the prepositions to complete gaps.(at,of,by,for,in,as,on,) I39;m archaeologist39;s assistent and i39;ve

Use the prepositions to complete gaps.(at,of,by,for,in,as,on,) I39;m archaeologist39;s assistent and i39;ve been working ___ a Roman fort __ two weeks . I39;ve always been interested ___ archeology,so when i saw the job advertisement ___the newspaper I applied immediately.I was lucky.Although i had no experiense __ working __ an crchaeologist ,I was offerd the job.so now i spend most of the day surrounded ___dust and dirt!