peter was one in the race哪里错了

Peter was in the race
Peter 当时正在比赛

不知道你要表达哪种：
彼得是比赛中的第一名： Peter was the first one/NO.one in the race.
彼得是唯一一位参赛选手：Peter was the only one in the race.

你是想说peter是比赛中的第一是么，
可以用first ，比如：Peter was first in the race.
也可以用Number One.比如：Peter was No.One in the race

这个翻译过来是:peter在比赛中是一

完全无里头, 改成"peter was one of the player in the race

Peter 当时正在比赛

one 不能和 the 放在一起， in the race已经代表了一场比赛了

Peter was the(不能少) first in the race