we don't have classes on sundays.中的sunday为什么要加"s'

we don't have classes on sundays.中的sunday为什么要加"s' We don't have any classes on Sunday.We _____ ___ on saturday and sunday ,we don't have any classes 的意思 We don't have any classes on Sunday.【同义句转换】 on saturday and sunday we don't have any classes 的意思 on saturday and sunday we don't have any classes 句意是什么, on saturday and sunday ,we don't have any classes 的意思是什么 my aunt don't work on sundays,这句话中的work要加S吗? We ______ (not have) classes on Sundays . We have no (class/classes) on Sundays. it was sunday,a never get up early on sundays.sunday为什么要加S we don't have any classes on weekends.class为什么要用负数,用单数不行吗