The rule is that every word has a cross structure (only one). Only the number of strokes, pronunciation and font structure can regulate Chinese characters. From these three aspects, we can find the law.

1, the number of strokes is force (2), stem (3), and (3), field (5), and the stroke rule is gone.

2. Pronunciation is Li (Li), Gan (gàn), and (jí), Tian (tián). The pronunciation of the first two sounds is the fourth sound, and the second sound of the last two sounds seems to be regular, but it is impossible to infer the following words according to this rule.

3. The rule of font structure is that every word has a cross structure, which can be used to judge the following words, so it can only be this rule.

Extended data:

The origin of the Olympics:

Professor Roman, a Romanian mathematician, proposed in 1 and 1956 that the first International Mathematical Olympiad (IMO) was held in Romania in July 1959. Only Bulgaria, Czechoslovakia, Hungary, Poland, Romania and the Soviet Union participated.

2. Since then, it has been held once a year (1980 only once), and the number of participating countries and regions has gradually increased. At present, there are more than 80 teams participating in this competition. China participated in the International Mathematical Olympics for the first time in 1985.

3. After more than 40 years of development, the operation of the International Mathematical Olympiad has been gradually institutionalized and standardized, and a set of established practices has been followed by previous hosts.