: The course focuses on a "step-by-step" accumulation of grammar structures. Simply copying an answer defeats the purpose of the repetitive drills designed to build "receptive muscle memory".
: If you make more than 20% errors, experts suggest re-doing the exercise after a few days without looking at the keys.
: Look for the book titled "Answers and Keys to English Step by Step" ( Ответы и ключи к учебнику Английский шаг за шагом ).