20以内三连减口算练习题(201).docx

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1、13-5-1 =20 - 12 - 8=15-7-5二17-2-5 =20-4-6=16-7-3 =17-5-4=8-1-7=19-2-11 =6-3-1=12-5-5 =13-2-11=7-5-2=14-7-7=20-3-4=15-2-9=17-7-3 =15-3-9=16-11-1=13-3-2 =18 - 10 - 5=15-4-2 =16-7-5 =13-9-1=20 - 13 - 1=18-6-1=17-2-9=19-7-12 =20-3-3 =19 - 13 - 6=19-6-12 =14-5-6=16-9-7=17-3-9=20-7-9=19 - 12 - 5二19 - 14 -

2、 4= 19-8-11=17-1-7=18 - 1 - 15 = 15-5-7=14-4-2 =6-1-2=13-6-4=12-6-3 = 14-2-6=18-3-9=20-13-2=19-11-7=16-1-7=7-2-5=16-5-9=18 - 14 - 4= 13-6-7=17-6 - 10=12-4-2 =18-1-9=19-3-8=16-14-1 =19-1-9=15-4-11 =18-10-1 =7-4-2=11-2-3 =10-2-4=19-4-2 =17-2- 10=13-3-9=18-14-1 =16-6-2 =18 - 12 - 6=9-7-2=10-4-3 =18 - 3

3、 - 11=9-2-6=20 - 11 - 7=17 -13-4=15-1- 10=17 - 10 - 4=13 - 12 - 1 =15-8-3 =20-4-5 =12-3-6=19-14-3 =18-14-3 =16 - 10 - 1=13-2-4=12-2-9=11-1-8=16-3-7=错误率,PH13-7-2 =20-3-15 =20 - 18 - 2=18-1-6=19-6-13 =19-5-11=18-6-2 =12-11-1=16-4-5二6-5-1=18-6-3 =19 - 1 - 11=13-2-2 =14-11-3 =12-6-6=10-4-1=13-3-4=19 - 1

4、0 - 5=15-9-5 =11-1-2 =16-13-1 =20-3-5=13-5-6=11-3-5=13-5-2 =17-11-4=18-6 - 10=19-9-4=20-3-7=19 - 11 - 6=20-1- 10=17-9-7=17-9-6=16-5-3 =19-4-4=12-7-3 =6-1-4=4-3-1=20-2-15 =16-1-8=16-8-6=4-2-2=20-11-2=16-1-1=15 -1 - 11= 15-1-1=20-7- 12=17-6-7=19-11-4=14 - 10 - 4=12-3-9 =9-3-5=17-8-7=5-2-2=14-3-1=19-2-

5、 12 =16-7-7=14-5-7=15-8-1=17-14-3 =16-7-8二17 - 3 - 10=8-1-6=19-8-4=20-2- 16=19-1-3 =17-4-1=19-1-8=15 - 10 - 4=10-3-2 =15-3-3 =20-8-9二14-6-5 =14-4-4=14-5-2 =20-9-2二18-6-8=11-6-3 =16-5-2 =19-5- 14=19-1-13 =16-4-11 =19-8-5二17-5-3 =14-1-8=16-4-10=15-6-4=15-4-8=12-1-6=19 - 13 - 1=15-3-1=16 - 14 - 2=20 -

6、3 - 11=11-2-7=19-5-9=20-2-8=16-4-6=8-4-4=20-15-2 =14-3- 11=20-15-4=17-1-4=18 - 10 - 2=20-6-2 =14-1-3 =17-4-7=10-2-1=13-2-1=18-3-1=20-8- 12=16-2-5=10-7-3 =9-1-1=15-7-6=19-7- 10=16-13-2=18 - 2 - 13=10-1-4=19-14-5 =20-1-2 =18-9-3 =9-7-1=10-2-2 =14 - 13 - 1=19 - 17 - 1=16-5-4=14-2-2 =19-5-4=18 - 12 - 5

7、=18-14-2 =8-3-3=17-2-1=12-1-3 =9-2-2=13-4-7=7-2-3=17 - 10 - 2 =18-8-6=20-8-11 =15 -12 - 2=18-5-1=18-6-12 =18-4-10=20-4-3 =16-3-4=17-6-2 =15-7-3 =17-6-1=16 - 1 - 14=19-4-6=17-1-3 =18-13-2 =10-4-6=13-9-2=11-8-3=14 - 11 - 1二14-2-7=20-3- 12 =12-8-4=19 -13 - 2=19-6-9=20 - 19 - 1=15-4-10=10-3-1 =17-2-7=16

8、-5-1=7-1-1=12-8-2 =10-1-9=18-9-5=12-7-5 =18-1- 10=14-6-2 =12-4-6=17-6-4=12-1-9=16-2-4=19 - 12 - 7=15-8-4=17-9-8=16-8-2 =14-7-4=20-2-9=19-2- 16=15 - 3 - 10=5-1-4=17-7-5 =19-7-4=20-6-5 =7-1-2=19-10-3 =19-8 - 10=15 - 10 - 1=15-1-7=9-2-3=18-7-2 =19-2-5 =8-5-1=20 - 10 - 1=13-5-8=14-5-3 =17-9-2 =17-14-2 =

9、18-9-4=13-8-1=10-8-2 =8-5-2=15-9-1=15-2-4=7-1-3二12-4-7=3-1-1=20 - 13 - 5=20 -11 - 8=20-7-4=11-4-3 =17-6-8=20-4-1=12-3-3 =20-4-12 =17-2-6=16-2- 10=19-7-6=14-2-12 =16 - 10 - 4=7-2-2=15-5-8=8-2-6=16-8-1=20-9-5二20-3-13 =16-6-9=17-9-3 =17-3-3 =12-3-8=20 - 12 - 7=19-4-15 =13-10-3 =19-8-3 =20-17-1 =6-2-1=9

10、-2-4=19-2-1 =9-5-4=18-2- 12 =20-9-4=19-4-12 =19-4-8=16-3-8=20-3 - 16=16-3 - 10=15-3-7=14-1- 11=16-8-7=20-1-7=17-2-8=18-6-9=12-1-7=17-2-15 =15-7-4=20-15-3 =13 - 11 - 1=5-2-3=9-5-2=18 - 12 - 1 =19 - 15 - 3 =16-6-3 =18-3- 12=20-9-8=19 - 10 - 6二15-10-5 =15-1-2 =18-4-11 =20 - 12 - 3 =13-1-5 =13-7-6=13-3-

11、8=15-6-8=19-3-1=16-7-2 =19-9-10=10-1-8=18-1- 12=17-4-2 =20-2-11=9-1-3=19-1- 10=16-6-5=7-4-3=20-7-8二13-6-1=20-8-1=11-5-5 =16-5- 10=19-3- 14=11-1-1=13-1-2 =15-7-7=20-5-6=20-2-13 =18-2-11=19-8-8=19 - 16 - 1二 19-4-10=15-1-13 =16-6-6=15-6-6=19 - 10 - 2 = 9-3-1=16 - 1 - 13 = 19-2-3 =17 - 3 - 12 = 14-3-6=9

12、-3-2=14-2-1=16-7-6=9-1-6=20-4-11=17-2-4=20 -13 - 3 =8-7-1=17-15-1=19-6-6=16-2-11 =11-2-9=16-1-6=10-4-5 =5-1-3=10-2-6=14-5-5 =12-2-1=19-2-7=19-8-7=17-11-2 =15-4-1=20-2- 12 =16-2-3 =6-1-3=15-6-3 =19-4- 14=13-2-3 =15-9-3 =20-1- 17=6-4-1=15-2-1=7-2-4=15-4-7=5-1-1=10-2-5 =20 -16 - 2=19-5-3 =12-2-2 =17-8-

13、8=18-8-2=10-2-7=20-8-4=15-7-8=20 -10 - 2=11-5-6=20-4-2 =8-4-1=18-4-8=19-2- 14=16-6-1=6-3-3=17 - 1 - 10=20-2- 14=15-11-4=5-4-1=9-3-3=12-9-3 =19 - 5 - 12 =18-1-11 =16-11-2 =19-2- 10-18 -13 - 3=19-4-1=11-7-4=9-4-1=19-3-7=20-1-3 =18 - 3 - 14=18-9-9=8-6-1=20-2-4=14-7-6=14-1- 10=17-5-2=18-2-6=18-11-3 =17-

14、1- 16=6-2-2=17 - 13 - 2 =7-2-1=18-5-5=11-5-4=9-3-6=16-9-2 =17-9-1=10-3-3 =15-6-7=7-1-4=9-2-5=16-1-15=16 - 10 - 2=20-3-1=16-10-3 =20 - 12 - 2 =17-16-1 =18-3-8=19 - 3 - 10=12-5-4=20 - 10 - 4=16-1-11 =10-1-6=7-3-4=15-3-6=18 - 5 - 10=9-5-3=9-6-3=17-8-3 =20-5-3 =12-5-3 =15-1-12 =19-5-2 =13-5-3 =18-7-9=8-

15、1-1=20-1-1=12-2-7=18-11-4=20-6- 14=20-7-5 =10-3-7=20-2-6=20 - 1 - 19=18-5-2 =20 - 12 - 5=17-7-8=20 - 10 - 8=17-3-7=12-7-4=20-2-5=20-1-5=15 - 12 - 1=11-7-1=11-3-2=20-1-13 =16-3-1=11-5-1=11-6-4=9-8-1二19-9-7=14-5-9=11-2-1=18-5-13 =14-6-1 =14 -10 - 2=17 - 11 - 6二16-6 - 10=20-9-3 =19-5-7=15 -14-1 =10-3-5

16、=17-1-2二18-6-11=16-1-9=8-1-3=20-4-16=12-3-5=14-3-8=11-2-4=19-9-9=12-1-5 =17-3-2 =17-9-4=19-2-6=17-7- 10=14-7-3 =18-8-5=20-8-5=11-6-5=16-7-4=15-3-8=5-2-1=17-6-6=18-7-3二15 - 1 - 14=6-2-4=20-4-8=18-2- 16=19-1-5 =19 - 1 - 14=18 - 16 - 1=19-9-6=13 - 1 - 12=10-3-4=18-4-5 =17-7-2 =19-3-9=18 - 10 - 8=11-6-1

17、=19-14-2 =20-1- 16=19-3-6=14-1-12 =11-4-7=16-4-12=17-5-5 =14-1-5 =17-3-5 =11-3-3 =8-2-2=19-11-8=20-8-8二13-3-5 =17-2-2 =18 - 15 - 1= 13-9-4= 19-6-7=18-2-8=15 - 5 - 10= 16-5-7=13 - 10 - 2 =20 - 17 - 2= 16-1- 10=17 - 12 - 4= 11-1-4=9-5-1=20-9-1二 6-3-2=9-4-5=15-5-9=20-5-1=11-4-6=19-3-4=18-5-7=10-2-8=4-1

18、-1=18-3-4=14-8-4=15-4-4=17-2-3 =19-9-5 =14-2- 10=8-2-1=13-9-3 =13-3- 10=18-8-7=20-6-6=17-3- 14=17-8-2 =20-1- 14=19-2-13 =10-5-2 =20 - 10 - 7=14-9-5=20-5-15=14-3-7=20-3-2 =19-8-2 =17-2- 12=20-7-6=10-9-1=14-9-4=12-5-1 =20-8-2 =19-4-9=16-1-4=12-1-8=13-6-5=20-14-5 =17-9-5 =15-1-3 =20-5-7=13-1-4=17-5-9=1

19、9-2-15 =20 - 10 - 10=20-6-13 =8-4-2=18-2-4=18-9-2二18 - 13 - 1=17-4-4=11-2-2 =16-2-8=15-3- 11=18-3-15 =20-4-4=20-7-1=8-3-1=14-4-7=20-7- 10=18-5-8=17-1-8=12-1- 10=13-6-3 =15-8-6=13-4-8=20 - 18 - 1=16-5-5 =20-1-11 =12-7-1=17-6-9=14-6-3 =12-10-2 =18-1-13 =10-5-4=19-9-1=18-8-4=6-1-5=17-1-9=11-3-1=17-3-13

20、 =10-6-1=13-2-5 =14-11-2 =19-9-8=13-5-5 =8-3-2=11-4-2 =12 - 1 - 11=20-6-7=13-5-7=14-2-3 =18-2-5 =19-9-3 =17 - 1 - 12=17-11-5 =16-8-5=14-3-9=18-6-7=11-8-2 =16 - 3 - 12=19-9-2=19 - 10 - 9 二14-8-1=20-8 - 10=8-2-4=20-4-10=13-1-3 =15-4-3 =16-4-7=20-2- 18=20 - 16 - 1=19-5-5 =15-2-8=20-6-1=13-6-2=16-2-7=13

21、-1-1=8-2-5=12-5-2 =20-3- 17=19-5-8=13-8-3 =17-8-4=18-7- 10=20-2- 10=11-1-3 =15-5-5=15-3-2 =12-1-2 =19 - 13 - 4=20-2-7=14-3-2 =17-5-11=18-9-7=13-4-5 =16-4-1=19-16-3 =13-4-3 =20-4-13 =8-6-2=20-17-3 = 13-7-4=18 - 10 - 6= 19-8-9= 20-5-5 =18-1-3 =18-8- 10=19-4-13 = 11-2-6= 13-4-2 =17-15-2 =15-3-5 =12 - 1

22、0 - 1= 11-3-4=11-9-2 =14-7-1=19 - 12 - 3二10-6-2 =15-11-2 =15-5-2=13-4-9=18-5-4=18-3-7=19-5-6=10-7-2 =14-1-1=17-1-1=12-6-2 =15-5-3 =15-5-6=15-2-6=18 - 15 - 3二12-8-1 =10-1-5 =13 - 1 - 10=16-9-6=18-11-2=14-4-1 =19 -15-4=19-7-11 =17-1-11 =20-7-13 =13-2-7=15-2- 10=6-1-1=17-1-6=16-4-8=18-15-2=18-8-9=19-1-

23、4=14-8-2 =16-2- 12 =16-6-7=18-2-7=18-4-13 =20-11-9=19-14-1 =19-1- 16=13-2-6=17-5-7=18-2-1=17-14-1 =19-6-1=19 - 5 - 10=10-5-1=13-2-8=17-7-4=20 - 16 - 4=错误率,PH16-5-6=14-6-7=16-9-3二15 - 13 - 1= 16-3-13 =19 - 13 - 5 = 11-2-8=17-4-12 =16-3-5 =3-1-2=18-5- 12 =20 - 12 - 1= 20-6-3 =20-4-7= 11-6-2 =18-1- 17=

24、19 - 12 - 1=10-4-2 =20-4-9=12-1-1=11-7-3 =19-6-11 = 20-8-6=16-11-3 =20-5- 10= 18-2-9=19 - 14 - 4= 19-8-11=17-1-7=18-1-15 = 15-5-7=14-4-2 =6-1-2=13-6-4= 12-6-3 =14-2-6=18-2-3 =20-7-7=20 - 14 - 6=13-8-4=14-2-9=4-1-2=13-5-1=20 - 12 - 8=15-7-5 =17-2-5 =20-4-6=16-7-3 =17-5-4=8-1-7=19-2-11=6-3-1=12-5-5 =1

25、3 - 2 - 11 =20-6-11=14-8-6=17-4- 10=9-6-1=8-4-3二16-11-1 =13-3-2 =18 -10 - 5=15-4-2 =16-7-5 =13-9-1=20 - 13 -1=18-6-1 =17-2-9=19-7-12 =20-3-3 =19 - 13 - 6=20-13-2 =19-11-7=16-1-7=7-2-5=16-5-9=18 - 14 - 4=13-6-7=18-1-4=9-4-5二15-5-9=20-5-1 =11-4-6=19-3-4=18-5-7=10-2-8=4-1-1=18-3-4=14-8-4=14-7-7=20-3-4=

26、15-2-9=17-7-3 =15-3-9=12-5-7=13-1- 12=10-3-4=18-4-5=17-7-2 =19-3-9=18 - 10 - 8=11-6-1=19-14-2 =20-1- 16=19-3-6=14-1- 12=11-4-7=16-9-7=17-3-9=20-7-9=19 - 12 - 5 =16-1-2 =19 - 11 - 8=20-8-8=13-3-5 =17-2-2 =18-15-1=13-9-4=19-6-7=18-2-8=15-5- 10=16-5-7=13 - 10 - 2=20 - 17 - 2 =17-2-3 =19-9-5=14-2- 10=8-

27、2-1=13-9-3 =13 - 3 - 10=16 - 10 - 5=20-3-9=14-1-4=14-2-8=12-4-4=13-4-6=14-1-13 =20-7-11=8-1-4=14-9-1 =18-1-1=15-1-6=17-5-5 =14-1-5 =17-3-5=11-3-3 =8-2-2=19-15-2 =18-7-4=13-7-3 =11-1-5 =17 - 1 - 14=16-2-9=14-4-9=12-5-6=16-1-3 =17-8-1=20-14-3 =19-1- 17=20-2-3 =11-1-4=9-5-1二20-9-1 =6-3-2=20-3-6=17-7-1=

28、19-3-2 =18-8-3 =20 - 13 - 7=14-7-5 =20-5-8=5-3-2=18-7-8=16 - 10 - 6=19-7-9=19-8-1=11-10-1=7-3-1=18-8-1 =14-12-2二17-6-3 =15-2-5=12-2- 10=13-6-6=20-8-7二14-2- 11 =7-3-3=19-1- 18=18-3-13 =16-7-9=7-1-6=17-4-5 =7-4-1=19-4-11 =16-5-8=9-2-1=14-5-1=14-8-5 =12-1-4=18-6-4=17 - 12 - 1=8-1-5=17 - 5 - 12=16 - 13

29、- 3=19-4-5二17-4-8=16-2- 14=15-1-4=20-1-4=8-2-3=10-1-3 =17-1- 13 =14-4-5 =错误率,PH18-9-1=14-6-8=17-8-5=19-2- 17=13-3-3 =19-7-1=15-10-3 =16-2-6=17-4-13 =7-6-1=20-9-7二12-2-5 =12-6-4=20 - 16 - 3=20-9-11=20 - 11 - 5=16-1-5 =9-4-4=20-2-2 =19-8-6=12-2-6=17 -13 - 3=11-3-8=12-4-8=19-7-5 =15 - 11 - 3二15 - 11 -

30、1=6-2-3=18 - 11 - 7=10-8-1=13-5-4=14-1-2=16-4-3 =19-6-4=14-3-5 =12-2-8=20-1-6=20 - 14 - 4=19-3- 16=12-9-1 =20-2-1=17-5-6=18 - 11 - 5=19-1-1=14-6-4=4-1-3=18 - 12 - 2 =20-1- 18=17 - 10 - 7=18 - 12 - 3二18-6-5 =17 - 10 - 6二12-3-1=18-6-6=14-3-4=18 - 10 - 7=13-11-2 =17-12- 5 =20-1- 12 =15-9-6=20-8-3 =10-1

31、-7=17-5- 10=18-2-15=20-9-9=19-5-1=20-9-6=5-1-2=19-6-5 =13-4-4=12-3-2 =17-4-6=20-6-9=16-3-2 =19 - 17 - 2二17-7-9=11-5-3 =19-1-6=18-4-2=14-4-8=11-9-1=14-3-3 =18-5-11 =13-4-1=14-10-3 =10-5-5 =14-4-3 =20 - 13 - 6=14-9-2=18-2- 10=17-3-6=12-2-4=19-6 - 10=17-3-8=17 - 11 - 1=13-7-5 =18-4- 14=19-7-3 =15-4-6=9

32、-1-8=12-4-1=16 - 12 - 3二18 - 13 - 5=18-2-2 =17-8-9=14-3- 10=12-6-1=12-2-3 =15-6-9二20 - 10 - 3= 20-11-1=20 -11-4=18-5-6=15 - 12 - 3二18-4-7=8-5-3=17-5-1=19 - 10 - 8= 16-9-1=16 -12 - 2=17 - 12 - 2 =11-8-1=12-9-2 =19 - 18 - 1=18-7-4=13-7-3 =11-1-5 =17-1- 14=16-2-9=14-4-9=12-5-6=16-1-3 =17-8-1=20-14-3 =1

33、9-1- 17=20-2-3 =14-1-7=9-2-1=14-5-1=14-8-5 =12-1-4=18-6-4=17-7-1=19-3-2 =18-8-3 =20 - 13 - 7=14-7-5 =20-5-8=5-3-2=18-7-8=16 - 10 - 6=19-7-9=19-8-1=11-10-1=19-2-9=18-9-1=14-6-8=17-8-5 =19-2- 17=13-3-3 =14-1-4=14-2-8=12-4-4=13-4-6=14-1-13 =20-7-11=8-1-4=14-9-1 =18-1-1 =15-1-6=18-4-3 =7-3-1=18-8-1=14-1

34、2-2 =17-6-3 =15-2-5 =12-2- 10=20-5-2=15-6-1 =9-1-2=20-5- 12 =9-2-7=18-2- 14=16-4-2 =15-5-4=18-3-6=16-11-4=12-3-4=2-1-1=17-7-6=13-3-7=19-4-7=20-4- 14=3-2-1=20-3- 14=18 - 10 - 4=17-8-6=14-9-3 =17-7-7=20-7-3 =18-4-9=13-1-8=13-7-1=16-3-3 =16-2-2 =13-1-7=11-3-7=20 - 14 - 1= 20-1-15 =17 - 10 - 1二18-10-3 =

35、20 - 12 - 4= 17-10-3 = 17-6-11=17 - 1 - 15 =5-3-1=19 - 10 - 4二7-5-1=18 - 12 - 4=15-2-12 =13-2- 10=12-4-5 =19-1-7=11-2-5 =17-4-11=16 - 5 - 11=14-5-4=20-1-9=15-2-11=13-1-6=9-4-2=19 - 12 - 2二13-3-6=13-8-2 =15-3-4=14-4-6=19 - 12 - 6二17-3-1=9-1-5二12-8-3 =19-6-8=9-6-2=9-1-4=17-1-5 =15-13-2=11-4-1 =17-4-3

36、=18-11-1=10-4-4=20 - 10 - 9=20-5-4=15-4-9=18-7-5 =16-3-9=20-15-1 =20-3- 10=7-3-2=20-9 - 10=15-7-1=9-1-7=16-9-5=19-7-8=10-5-3 =10-1-2 =18 - 1 - 16=10-2-3 =20 - 5 - 14=19-3-3 =15-1-5=13-3-1=11-7-2 =20 - 11 - 3=10-6-3 =17 - 3 -11=15-2-3 =16-6-8=15-8-2 =16-2-13 =17-13-1=18-1-7=8-3-5=18-3-3 =18-8-8=19 -

37、10 - 1二19-1-2 =18-7-7=10-1-1=18-4-12=18-4-1 =20-7-2二17-11-3 =18-3- 10=19-3-11 =18-3-2 =16-7-1=15-10-2 =15-1-9=20 -15 - 5=20-5-11 =19-11-2 =20 -10 - 5=13-1-11 =16-3-6=18-1-2 =16-2-1 =16 -11 - 5=17-5-8=11-1- 10=15-9-2 =19-16-2 =16-4-4=11-5-2 =4-2-1=19 - 3 - 15=19-2-4=20-14-2 =14-4-10=19-11-3=10-7-1 =1

38、1-4-4=16 -12-4=20-2- 17=18-1-8=19-2-8=9-4-3=20 - 10 - 6=16-1-12 =15-8-5 =19 - 3 -12 =15-7-2 =8-1-2=6-4-2=18-4-6=15-6-2=9-3-4=19 - 1 - 15 =18 - 17 - 1二17-4-9=19 - 15 - 1=15-9-4=18-13-4=19-11-5 =20-5-13 =20-6-8=14-1-9=13-7-2 =20-3-15 =20 - 18 - 2=18-1-6=19-6-13 =19-5-11 =18-6-2 =12 - 11 - 1=16-4-5 =6-

39、5-1=18-6-3 =16-12-1 =13 - 10 -1=12-3-7=18-1-5=19-1- 12 =12-4-3 =17-6- 10=12-4-2 =18-1-9=19-3-8=16 - 14 - 1=19-1-9=15-4-11=18 - 10 - 1=7-4-2=11-2-3 =10-2-4=19-4-2 =7-1-5=19-7-7=12-7-2 =18 - 16 - 2 =11-1-9=10-4-3 =18 - 3 - 11=9-2-6=20 - 11 - 7=17 -13-4=15 - 1 - 10=17 - 10 - 4=13 - 12 - 1二15-8-3 =20-4-

40、5 =12-3-6=19-14-3 =13-2-2 =14-11-3 =12-6-6=10-4-1 =13-3-4=19 - 10 - 5=19-2-2 =15-1-8=14-3-1=19-2- 12 =16-7-7=14-5-7=15-8-1=17-14-3 =16-7-8=17-3- 10=8-1-6=19-8-4=13-3-9=18-14-1 =16-6-2 =18 - 12 - 6=9-7-2=20-4-15=15-9-5 =11-1-2 =16 - 13 - 1二20-3-5=13-5-6=11-3-5 =13-5-2 =17-11-4=18-6 - 10=19-9-4=20-3-7=19 - 11 - 6 二13-2-4=12-2-9=11-1-8=16-3-7=12-6-5 =6-1-4=4-3-1=20-2-15 =1