during the week居然只有五天

during the week不包括周六和周日，如《牛津高级学者词典》有下述例句，

【例句2】I go out most weekends, but rarely during the week. （我大多数周末都出去，但工作日很少出去。）[牛津高级学者辞典]

但针对这两个例句的week释义是the five days other than Saturday and Sunday （除周六和周日外的五天）。

《柯林斯高级学者辞典》、《剑桥高级学者辞典》和《朗文当代英语词典》等主流词典对during the week的释义都是如此。例句如，

【例句3】We're usually too tired to go out much during the week.(我们通常太累了，工作日不能出去太多。) [剑桥高级学者辞典]

【例句4】 I don't see her during the week. (我这个工作周没见到她。)[朗文当代英语词典]

英式英语也用in the week表示“周一到周五”，如

【例句5】I never have the time to go out in the week. （我工作日没时间出去。）[牛津高级学者辞典]

【例句6】They arrived at the weekend and gave three concerts in the week. （他们于周末抵达，并在工作周举办了三场音乐会。） [柯林斯高级学者辞典]

但in the week更常见的用法是“在星期日到星期六时段内”，如

【例句7】There are seven days in the week. (一周有七天。)

“周一到周五”也可显表达为workweek(美式英语)或working week(英式英语)。若对某个人，星期六也工作，那么workweek也包括星期六。

“周一到周五”的其中一天叫weekday。

星期六和星期日合称的“周末”是weekend。

为什么有上述during the week这样的用法，原因待考。有可能是它的the week和on the weekend的the weekend形成了配对。