DESCRIPTION: 21 KINDS OF FUNCTIONS, MORE THAN 50,000 TOPICS ABUNDANT IN CONTENT. FOUR KINDS OF DIFFI >>Product Details:--21 KINDS OF FUNCTIONS,--MORE THAN 50,000 TOPICS ABUNDANT IN CONTENT.--FOUR KINDS OF DIFFICULTY DEGREE AND 2 KINDS OF SPEEDS,--OFFER VARIOUS KINDS OF STUDY CHOICES.>>PACKING:-- 1 PC. PER BOX, 20 PCS. PER CARTON-- N.W.: 14.50KGS G.W.:17.00KGS-- MEAS: 55.5X29.5X38CM Educational ...