Lesson 1, never put your net in the baggage compartment.

第一课，一定不要把捕虫网放在行李箱里。

The working assumption is that someone with access to the aircraft's baggage compartment was able to insert an explosive device inside or on top of the luggage shortly before the plane took off for St. Petersburg.

调查人员认为就在飞机前往圣彼得堡的不久前，有行李员将炸弹放进或放置在了行李箱上。