1, the last fall means: the first Geng day after beginning of autumn is the last fall. It usually refers to the day from the first Geng Day after beginning of autumn to the day before the second Geng Day (* * * ten days). Also called terminal voltage, three volts. Until the last day of 10.

2. The first night means that the third Geng Day after long summer is the first day of dog days, which usually refers to the period from the third Geng Day after long summer to the day before the fourth Geng Day. Also known as Fu Tou.

3. It first appeared. According to China's calendar, it was the beginning of a real summer. People often say: heat is at three volts, and cold is at three or nine. Dog days are the season with the highest temperature and humidity in a year, which can be divided into three days: the first, middle and last days, in which the first and last days are fixed as 10 days, some years are 10 days, and some years are 20 days. At the beginning of the incubation period, it is called entering or alternating, and at the end of the incubation period, it is called appearing. Lodging days depend on lodging time, generally before July 28th, lodging for 20 days, lodging 10 days.