根据短文意思和所给首字母，写出一个完整正确的单词．
In early human history，people found that the changes of"light and darkness"seemed to （61）h again and again．The sun rises in the east，（62）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 （63）l ．They counted the days （64）t passed from the sun's highest position （位置） until it returned to that position．That was three （65）h and sixty-five days．That's just one year．