For days, Iran had been claiming it was a mechanical error that brought the airplane down, killing all 176 people onboard.

数天以来，伊朗一直坚称这起致176人死亡的坠机事故的原因是机械故障。

Theories range from espionage, sabotage, enemy fire, and mechanical error.

理论范围从间谍活动、破坏活动、敌人火力和机械错误。

Investigators are trying to figure out whether it was human or mechanical error that caused an Amtrak passenger train to derail in Philadelphia Tuesday.

调查人员正试图确定是否是人力或机械误差造成周二美铁客运列车在费城脱轨。