Make sure the PDF you are reviewing is the "upd" (updated) version to match the current textbook printing.
Use a red or green pen to mark wrong choices based on the updated key. This provides visual feedback on your personal weak spots. english grammar eka zambakhidze answers upd
Older answer keys may reflect outdated prescriptive rules that native speakers no longer follow. For instance, the prohibition against splitting infinitives or ending a sentence with a preposition is largely ignored in modern writing. An updated answer key will reflect current practice, not 19th‑century strictures. Make sure the PDF you are reviewing is
: The North , the South , the East , the West . not 19th‑century strictures. : The North
