In early human history, people found that the changes of “light and darkness” seemed toh__________ again and again. The sun rises in the east,p___________ light and heat and goes down in the west, causing darkness. This “light and darkness” was one day.
People also saw the sun rise in the sky, sometimes higher but sometimes l__________. They counted the days t___________ passed from the sun’s highest position (位置) until it returned to that position. That was threeh___________ and sixty-five days. That’s just one year.