What is the rhyme pattern of poetry based on?

The rhythm of poetry, ancient poetry is based on the rise and fall of flat tone to form the rhythm, and it is to retain the last vowel.

take for example

Goose, goose, Xiang Tiange, white hair floating green water, Anthurium playing green waves.

One or two sounds are flat, three or four sounds are gouged out, and the first, second and fourth vowels e, o, e and o are similar in pronunciation. Moreover, the first, second and fourth sentences are all flat, which are consistent and catchy to read.