1, we can find that 5 is one less than 6; 12 is seven to five; 12 is one less than 13; 13 is 7 more than 6.

2. If two horizontally adjacent dates are selected, and their sum is 17, then the 8th and 9th dates are selected.

3. If two vertically adjacent dates are selected and their sum is 27, select 10 and 17.

Extended data:

Teaching plan for year, month and day of mathematics in grade three;

Guided by the new curriculum standards, we should creatively use teaching materials, take mathematics in students' life, learn useful mathematics, and solve simple problems in life with mathematical knowledge as the basic concepts, and cultivate students' ability to find and solve problems on the basis of independent exploration and cooperative exchange, so that students can receive ideological and moral education. Realize that there is mathematics everywhere in life, and further cultivate cooperation consciousness and skills.

Teaching emphasis: know the time unit year, month and day, and understand the relationship between them. Teaching difficulties: the memory of the big moon and the small moon, and the judgment method of the normal year and leap year.