讲一下这道题，用中文---Challenge 1 **Question Stem:** Put 2 to 9 in appropriate places so that the sum of the 3 numbers on each line equals 18. (Each number can only be used once.) **Diagram Description:** The diagram consists of a square or rectangular outline formed by blue-green lines, with a yellow cartoon bear icon placed at each corner and in the middle of each side. There are a total of 8 bears arranged along the perimeter. The lines connect these bears, forming four segments on each side, with a bear at the beginning, middle, and end of each segment. Each of these lines represents a line on which three numbers must sum to 18. There are four such lines, corresponding to the four sides of the square/rectangle. To the right of this diagram, there is a list of numbers from 2 to 9, arranged vertically in two columns. Each number (2, 3, 4, 5, 6, 7, 8, 9) is displayed next to a blue cartoon bear icon. These are the numbers that must be placed in the positions occupied by the yellow bears in the diagram. **Available Numbers:** 2, 3, 4, 5, 6, 7, 8, 9