As shown in the following table, fill in an integer in each small cell from left to right, so that the sum of integers filled in any three adjacent cells is equal, then the number in the 20th12nd cell is ().

| 3 | a | b | c |- 1 | | | 2 |…

A.3 B.2 C.0 D.- 1

Answer d

analyse

Analysis: According to the law in the topic: the sum of integers filled in any three adjacent grids is equal, the values of A and C can be obtained, and the cyclic law can be obtained, from which it can be judged.

Solution: According to the meaning of the question, 3+a+b=a+b+c,

Then c = 3；;

Similarly: a+b+c=b+c- 1, then a=- 1,

Then the numbers in the grid are: 3,-1, b three numbers appear in cycles, and 20 12÷3=670…2, so the numbers in the grid of 20 12 are-1.

So choose D.