1. 我要休一天班,从语法上讲:
I woulk like to take a day off. 或者 I'm going to take a day off tomorrow. 都可以。
" I am taking a day off tomorrow", 从语法上讲,有点不妥,因为是"tomorrow",最好用将来时" be going to" 来表达,所以用"I am going to take a day off tomorrow" 更好。不过,在口语里,说“I'm taking a day off tomorrow.” 也可以接受的。
2. 如果你要用礼貌的方式表达“想休一天班”,最好说出休一天班的原因,比如:
Mr.../ Ms..., is it OK/alright for me take a day off tomorrow because I ...?
Mr... /Ms..., do you think it might be possible for me to have a day tomorrow? Because 1...
以上是我个人浅见,也不知道是否回答了你的问题,仅供参考。