well-studied russian

• проштуди́рованный

  well-studied, thoroughly studied, perused

• штуди́рованный

  studied, well-studied, thoroughly researched

Examples

• После трех лет изуче́ния францу́зского Том мо́жет говори́ть на нем довольно хорошо.

  Having studied French for three years, Tom can speak it quite well.