对于易受污染和破坏的证据材料,以下哪种行动是错误？（ ）

　Area controllers watch dozens of aircraft at once on huge radarscopes.

　I look strong, but actually my health is very poor.

　A service agent must know whether a passport check is required or not.

　The airlines prefer to have the ticket blow up as far in advance as possible .

　Air travel is just as safe and comfortable as any other kind of travel.

　The purpose of the oxygen system is to provide oxygen for the flight crew and passengers when required. Two independent oxygen system are installed in B737.

　Position/remove wheel kicks please.

　The emergency exits are located on either side of the plane.

　The brakes are unbelievable .

　He has demanded that we fly to xx, otherwise he is threatening bomb the plane and kill the hostage.