Very confused by the unexpected rejection of a/the. Sometimes the articles are demanded or expected other times they are not for the exact same phrases
Why isn't "the student's book" a valid translation -- is there a reason or just an oversight?
If you think you are right, even if you aren't sure, report it. You can always come to the comments and say "I've reported, but I'm not sure, is X also right?" You won't be penalised for wrong reports made in good faith.