是on weekdays还是on weekday?

是on weekdays还是on weekday? 是on weekday还是on the weekday是on the weekend 还是on weekend on weekdays还是at weekdays on weekdays,at weekdays和on weekday,分别是什么意思?它们的区别分别是什么 on weekday 和on weekdays 一样么?还有on weekend 和on weekends 一样么 是on the moring of weekday 还是 in the of weekday? weekday 和weekend用on还是at 后天期末on weekdays 还是in weekdays?in the weekends during the weekday还是during the weekdays on weekday、on weekday的意思 在周末英语怎么说是on weekends还是at weekends.在工作日是on weekdays吗? weekday和weekend前面用in,on还是at