The seven days of the week were based on the observation of the waxing and waning of the moon.
Through the observation of the waxing and waning of the moon, the ancients found that the time from half full moon to full moon and from full moon to half full moon was 7 days respectively, from half full moon to the disappearance of the moon, and from the disappearance of the moon to half full moon was 7 days respectively. Thus, people divided a month into four weeks and seven days into a cycle.
The week as a period of time originated in Babylon. The Babylonians had the system of the week in the 7th and 6th centuries BC. They divided the month into four weeks, with seven days in a week. The Ancient Babylonians built altars of seven stars to worship the star god. The seven star altar is divided into seven layers, each layer has a star god, from top to bottom is the sun, moon, fire, water, wood, metal, earth seven gods.

#卡姐日翻# Day 61
Thus the American president and vice-president have surnames starting with B and C respectively; and 26 of GeorgeBush's predecessors (including his father) had surnames in the first half of the alphabet against just 16 in the second half.
【解析】该句子的主干是由 and 连接的两个分句，即 American president and vice-president have surnames, and 26 of… had surnames。第一个分句的宾语 surnames 后是分词结构 starting with 作定语；第二个分句宾语后紧跟的介词结构 in the first half of the alphabet 作定语.
【句子翻译】因此，美国的总统和副总统的姓氏字母分别以 B 和 C 开头，而乔治·布什的祖先中，有 26 位姓氏字母排在了字母表的前半部分，只有 16 位排在了后半部分。

#卡姐日翻# Day 61
卡姐觉得这里的人名大家或多或少应该能猜出来哈
老规矩，九点半公布译文和解析
积极参与认真订正，就可能收到卡姐的小奖品噢~
Thus the American president and vice-president have surnames starting with B and C respectively; and 26 of GeorgeBush's predecessors (including his father) had surnames in the first half of the alphabet against just 16 in the second half.