Ключевые слова: alphabet, back, basic, beginner, block, business, common, concept, education, essential, fundamental, general, guide, guideline, how, idea, important, interest, key, knowledge, language, learning, letter, level, life, lifestyle, message, method, minimum, offer, policy, practice, primary, principal, principle, program, purpose, quote, requirement, right, simple, simplify, skill, standard, starting, study, supply, way, wood, word,