文档介绍：20以内加减法口算题(逆向思考题)20= 33-() 16 = ()+0 15 = 8+() 12 = 18-() 13 = 20-() 20 = ()+818 = ()-7 26 = ()+5 20 = ()-1 15 = ()-6 26 = ()+8 12 = ()-620 = 3+() 19 = 5+() 12 = 25-() 12 = 6+() 11 = ()-6 24 = 34-()13 = ()-3 17 = 27-() 12 = ()-3 20 = ()-10 21 = ()-5 19 = ()+220 = ()-3 128 = 4+() 13 = ()+5 12 =23-() 10 = 23-() 16 = ()+416 = 4+() 11 = ()-9 11 = 19-() 10 = ()-3 18 = ()-1 24 = ()-624 = 30-() 12 = 19-() 11 = 2+() 15 = 30-() 21 = 25-() 18 = ()+312 = 25-() 22 = ()-4 17 = ()-9 14 = ()+1 19 = ()+2 22 = 29-()24 = 7+() 17 = ()+5 27 = 18-() 20 = 1+() 17 = ()+1 14 = 18-()22 = ()-6 20 = 16+() 17 = 8+() 16 = ()-3 20 = 14+() 23 = ()-714 = ()+2 17 = 5+() 20 = 4+() 15 = 29-() 20 = ()+5 20 = ()+523 = 30-() 20 = ()-3 17 = ()+8 12 = 26-() 20 = ()+9 22 = ()-418 = ()-1 11 =26-() 16 = 14+() 22 = ()-7 14 = 26-() 16 = ()+615 = ()-5 12 =18-() 13 = ()-4 15 = ()-7 18 = ()+2 20 = 13+()19 = 4+() 13 = 20-() 15 = 20-() 19 = 8+() 14 = 4+() 26 = ()-013 = ()-7 18 = ()+9 19 = ()+3 11 = ()-6 25 = ()+5 15 = ()+227 = ()+6 20 = 10+() 21 = ()-9 20 = 30-() 15 = ()+2 24 = ()-618 = 29-() 25 = ()-3 18 = 14+() 15 = ()+0 17 = ()+4 12 = 27-()20 = 10+() 18 = 20-() 23 = 14+() 18 = 5+() 14 = 27-() 18 = ()+719 = ()+6 20 = ()+6 17 = ()-2 2