英语：at weekends为什么不用on weekends?详细!

英语：at weekends为什么不用on weekends?详细! what do you usually do at weekends?at weekends为什么不用介词on i don't like working at night and weekends.这里题目用的是and,为什么不用or? 这个英语句型对吗?I usually gets up at nine o'clock in the morning on weekends. 在周末英语怎么说是on weekends还是at weekends.在工作日是on weekdays吗? 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 是on the weekends还是at she weekends详细和为什么 是“at the weekends还是“at weekends? 一篇以《at the weekends》为题的英语小故事 英语好的进,Staff:pupil ratio including at weekends. 这句英语句子有没有错误?I go to bed at nine o'clock on weekends or holiday night.有没有错误.急! Mary gets up at nine o'clock on weekends .(用频度副词always替换)Mary ____ ____ up at nine o'clock on weekends He got there at around 4o'clock in the afternoon.为什么用around不用about at weekends和on weekends的区别 为什么weekends可以加at为什么weekdays前面不能加at At 7 o'clock mi father (leaves) work by car every day.六年级英语问题7 o'clock mi father (leaves) work by car every day.为什么用“leaves for”而不用“is leaving for”呢?请写出原因,谢谢. she usually gets up at about seven o”clock on weekends My cousin,Jim,_____(get)up at 6 o'clock in the morning on weekends