Fun fact, the suffix "ben" means "in" and adding a "t" at the end of the word makes it accusative, so that should help you remember this word
Your sentence is correct. There is a slight difference between 'bent' and 'benne': 'benne' refers to a definite object (e.g. asking 'what's in it' while pointing to a box), and is used more frequently. The duolingo sentence in everyday speech may only refer to rooms, buildings or large, enclosed spaces.