The phrase "study at separate" can be rewritten in several ways to convey the same meaning. For instance, you can use "study independently" or "study on your own" to indicate that each individual is undertaking their learning experience without interacting with others. "Study separately" and "study apart" are synonyms that also indicate the same thing. Moreover, you can use "individual study" or "self-directed study" to mean that each person is responsible for their learning and studying. Lastly, "solitary studying" can also be used to signify that an individual is working alone without any external support. All these synonyms are useful when talking about studying without any collaboration or interaction.