1
on weekdays
表示“在平日”或“在工作日”时，介词常用 on。
The library closes at 9 p.m. on weekdays.
图书馆在工作日晚上九点关门。
平日；工作日
先理解核心含义，再看它在真实句子里的用法。
平日；工作日
any day of the week except Sunday (and sometimes also except Saturday)
The library closes at 9 p.m. on weekdays.
图书馆在工作日晚上九点关门。
一周中的任何一天,除了构成周末或每周唯一休息日的那些天；即:
Any individual day of the week, except those which form the weekend or the single weekly day off; that is:
除星期日以外的任何一天(有时也除星期六以外)
any day except Sunday (and sometimes except Saturday)
I prefer to go to the supermarket on a weekday, when it is less crowded.
我更喜欢在工作日去超市，那时人比较少。
The museum is open on weekdays from nine to five.
博物馆周一至周五的开放时间是上午九点到下午五点。
She wears casual clothes on weekends, but she has to wear a suit on weekdays.
她周末穿休闲装，但工作日必须穿西装。
表示“在平日”或“在工作日”时，介词常用 on。
The library closes at 9 p.m. on weekdays.
图书馆在工作日晚上九点关门。
every 后接单数名词，所以用 weekday 而不是 weekdays。
He goes for a run every weekday.
他每个工作日都去跑步。
weekday 可以像形容词一样放在名词前作定语，例如 weekday mornings、weekday trains。
Weekday traffic is lighter than weekend traffic.
工作日交通比周末交通更顺畅。
Not this
I go to English class in weekdays.
Use this
I go to English class on weekdays.
表示“在每个平日/工作日”时，介词用 on，不用 in；in 用于年、月、季节或一天中的时段，不能与 weekdays 搭配。
Not this
She works on weekday.
Use this
She works on weekdays.
weekday 是可数名词；“每逢平日”指习惯性动作时要用复数 weekdays。若用单数，则应说 on a weekday，表示“在某个工作日”。
Not this
Today is weekday.
Use this
Today is a weekday.
weekday 是可数名词单数，作表语时前面需要加不定冠词 a，即 a weekday；不加冠词不符合英语语法。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
在工作日；在平日
Traffic is heavy on weekdays.
工作日的交通很拥堵。
每个工作日
The library opens at nine every weekday.
图书馆每个工作日九点开门。
工作日的早晨
We have staff training on weekday mornings.
我们工作日的早晨有员工培训。
工作日的晚上
She goes to yoga class on weekday evenings.
她工作日的晚上去上瑜伽课。
工作日的日程安排
My weekday schedule is packed with meetings.
我工作日的日程安排全是会议。
一个典型的工作日
A typical weekday starts with a quick breakfast.
一个典型的工作日从一顿快速的早餐开始。
只在礼拜天虔诚、平日却品行不端的人；伪善者
He goes to church every Sunday, but he's a Sunday saint and a weekday sinner.
他每个星期天都去教堂，但只是礼拜天装虔诚，平日照样做坏事。
发长 /iː/ 音 (如 see, free)
Use weekday naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
先把 weekday 拆成 week + day：一周中的日子；再记住 weekend 是周末，weekday 就是非周末的平日。
语域：neutral 常见场景：日历与日程安排、工作或学校作息、日常口语对话 weekday 是日常中性用词，通常指一周中非周末的日子（多指周一至周五），比较常见于日程安排和商务场合；具体是否包括周六需根据上下文判断。
day, today, birthday, Friday, and play rhyme with the final /deɪ/ or /eɪ/ of weekday (/ˈwikˌdeɪ/). Weekend shares the same 'week' spelling but does not rhyme: it ends in /ɛnd/, not /deɪ/. In casual speech, the -day ending can sound like /di/ in some compounds.
Dictionary facts from DICTIONARY_API_DEV, ECDICT, WIKTIONARY.