3个英语问题不懂,1.什么时候用on the stage 什么时候用 in the stage?2.我给律师寄了一封信,

英语on the stage on stage 是on the stage 还是in the stage on the stage和in the stage的区别是啥? on stage 与on the stage的区别 at the stage 与 in the stage 的区别 英语单选look at the girls on the stage. on stage中间可以加the吗 1.all the a_smiled when Zhou Libo appeared on the stage.2.my 什么时候用in the weekend什么时候用on the weekend什么时候用at the weekend? 英语：at a later stage /in the early stage 为什么一个是at 一个又是in呢?=.= 初中英语什么时候用on 什么时候用on the?（in/in the） The curtain often ______(hang) in front of the stage.答案给的是ha