The phrase 'be inside' can be replaced with a number of synonyms, depending on the context. For example, 'reside in', 'dwell within' or 'occupy' can be used when talking about someone living in a particular place. When referring to being enclosed or surrounded by something, 'be within', 'be contained in', or 'be enveloped by' are all reasonable alternatives. For a more specific use, such as referring to the contents of a container, 'be held within', 'be stored in' or 'be included in' could be used. Overall, there are numerous synonyms that can be used to replace the phrase 'be inside', depending on the context.