The National Transportation Safety Board says a preliminary exam shows evidence of metal fatigue on the Southwest Airlines jet engine that blew apart amid air.

美国国家运输安全委员会(National Transportation Safety Board)表示，初步检查结果显示，西南航空(Southwest Airlines)的喷气发动机出现了金属疲劳现象，致使引擎在空中爆炸。

One of the biggest advantages of taking these preliminary exams is that you can get to know the testing process and the types of questions you'll need to answer.

参加这些初试的最大好处之一是你可以了解考试的过程和你需要回答的问题的类型。