In he short story, where have you gone charming billy, how does the author use juxtapostition to show how paul berlin has changed through his experience of seeing billy die?

Idon't know which one from these two forms is correct! "he believed that the technology of the future would allow robots to do the same tasks as a human." or "he believed that the technology of the future would have allowed robots to do the same tasks as a human. , it's ! i need your !