For example, eight teams are divided into four groups. Write eight notes, two symbols of 1, two symbols of 2, two symbols of 3 and two symbols of 4. Eight teams draw lots in turn. The two teams drawn with the number 1 will compete, the two teams drawn with the number 2 will compete, the two teams drawn with the number 3 will compete, and the two teams drawn with the number 4 will compete.