Ключевые слова: abstract, accept, answer, approve, background, billboard, black, blackboard, board, chalk, chalkboard, check box, checkmark, choice, classroom, concept, confirm, correct, cross, decision, dirty, draw, drawing, eduction, erase, exam, examination, fail, grunge, handwriting, mark, multiple, pass, positive, reminder, right, scratch, select, selection, sign, success, symbol, texture, tick, true, used, white, wooden, yes,