Community pages on VK often host PDF versions of the student books (SB), workbooks (WB), and teacher's books (TB) for the 2016–2021 editions.
If you are looking for specific answers to exercises, these platforms provide step-by-step solutions for both the student book and the workbook: Community pages on VK often host PDF versions
Online resources for by M.Z. Biboletova include digital textbooks, workbooks, and ready-made homework solutions (GDZ). Ready-Made Homework Solutions (GDZ) Community pages on VK often host PDF versions