What is the meaning of "Li" in beginning of spring and Long Summer? Why use "reason" instead of "yes"

The intention is to establish, indicating the beginning of solar terms in spring, summer, autumn and winter. Twenty-four solar terms originated in the Yellow River Basin. As early as the Spring and Autumn Period, four solar terms were set, namely, mid-spring, mid-summer, mid-autumn and mid-winter. After continuous improvement and perfection, by the Qin and Han Dynasties, the 24 solar terms had been completely established. In BC 104, the taichu calendar written by Deng Ping officially set 24 solar terms in the calendar, and defined the astronomical position of the 24 solar terms. The time for the sun to travel once every 15 degrees along the longitude of the Yellow River from zero degree is called? A solar term? . It runs 360 degrees every year, and * * * experiences 24 solar terms, twice a month. Among them, what is the first solar term of each month? Solar terms? Namely: 12 solar terms such as beginning of spring, Jingzhe, Qingming, Changxia, Mangzhong, Xiaoshu, beginning of autumn, Bailu, Hanlu, beginning of winter, heavy snow and slight cold; What is the second solar term every month? Gas? There are 12 solar terms, such as rain, vernal equinox, Grain Rain, Xiaoman, summer solstice, summer heat, early summer heat, autumn equinox, early frost, light snow, winter solstice and great cold. ? Solar terms? And then what? Gas? Alternately, each time lasts 15 days, and now everyone is released? Solar terms? And then what? Gas? Collectively referred to as? Solar terms? .