Is the following sentences acceptable?
Once I took the train back to Taipei from Ilan. In the halfway Juifang station, a group of high school students got on the coach. Crowding outside the toilet, they were noisily laughing and joking as if there were no one else. I just came out of the lavatory, while the train was making a turn; I hit one of the students.
"Coach" is used for buses, not for train cars in AmE. (Even then "coach" is only used to make a bus sound fancy.) I would say "a group of students got on the car."
"Coach" is fine in BrE for the separate sections of a train.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
In the last sentence, should it be better to add an adverb 'accidentally' as written：
As I came out of the lavatory, while the train was making a trun, I accidentally hit one of the students.
Or "....accidentally bumped into one of the students."