on weekends 变为什么疑问词?

on weekends 变为什么疑问词? on weekends、at the weekends、at weekends、on the weekends有什么区别 he often watches TV on weekends.（变为一般疑问句） I often play foodball on weekends.变为否定句 All students watch TV on weekends.变为否定句 on weekends和at weekends有什么区别? 区别at the weekends,on the weekend,at weekends,on weekendsat the weekends,on the weekend,at weekends,on weekends都有些什么区别?各自的意思是什么? on weekends on weekends. on weekends at weekends have a weekends的区别.有什么区别 关于on weekends和on the weekends的问题是on weekends还是on the weekends,还是两者都可以?怎么用?与on the weekend有什么区别? What do you often do on weekends?什么What do you often do on weekends? on weekend和on weekends有什么区别 I usually go to school on foot应该用什么疑问词shool是疑问词 on weekends和on the weekend 有什么区别?on weekends和on the weekend 之间有什么区别? 在周末的英语除了on the weekends 和at the weekends 以外还有什么表达方式 the supermarket is too c什么 on weekends on weekends与this weekend有什么区别