Hi Helen! How are you? Good to see you again. :) "in", "for", and "at" are used interchangeably in most cases. As a guideline, you work >for< an employer, >in< a department, >at< a location. For example, you could work >for< McDonalds, >in< the finance department, >at< the research facility. 1) I work at a radio station 2) I work in a radio station 3) I work for a radio station They are all correct! Though they say something slightly different. But it's clear you are working there, which is what you want to say, right?

Work in /at a radio station > they are both good . "At" highlights the location you are in when working , which is a radio station. "In" highlights the area you are in when working , which is inside a radio station. You can use "for" as well . All points to the where you work . All depends on how you want to said it.