When I arrived at the station, a corpse was discovered in the sleeper car.
"駅に着いたとき、寝台列車の中から死体が見つかった" は英語で
When I arrived at the station, a corpse was discovered in the sleeper car.
といえます。
寝台列車
- sleeper car
- sleeper
- sleeping car
見つかった
- found
- discovered
When I arrived at the station, a corpse was found in the sleeping car.
Someone found a dead body on the sleeper car when the train arrived at the station.
この場合、次のような言い方ができますよ。
ーSomeone found a dead body on the sleeper car when the train arrived at the station.
「列車が駅に着いた時、寝台車から死体が見つかった」
a dead body「死体」
sleeper car「寝台車」
ご参考まで！
アメリカ合衆国 
カナダ 
