What do you do on Mondays?We have math on Mondays.这些句子中的Monday加S,语法上是怎么解释的?

what do you do on what do you do on the weekend what do you do on the weekend? What do you do on Sundays? what do you do on sundays? What do you do on weekends是什么意思 What do you usually do on weekends? What do you do on the weekend? What do you often do on what do you do on sundays?汉语 What do you do on Sunday是什么意思 What do you do on Sunday morning? what do you do on thanksgiving What do you usually do on Saturdays? What do you do on Saturdays What do you do on week-ends? what do you do on saturdays?是什么意思 do,what ,do ,you ,Thanksgiving Day ,on )