Airline operators are encouraged to evaluate their particular 737NG operating environment, accompanied with debris findings at time of leaning to identify and implement （执行）the most effective and economic maintenance interval.
鼓励航空公司运营商评估其特定的737NG运行环境，并在倾斜时发现碎片，以确定和实施最有效和经济的 维护间隔
A.Airline operators should determine and carry out the most effective and economic maintenance interval after *evaluating their particular737NG operating environment and the debris found when cleaning. B.In order to find the most effective and economic maintenance interval, airline operators have to evaluate and clean the debris accumulated in particular areas of 737NG. C.Before identifying the most effective and economic maintenance interval, airline operators can evaluate the 737NG operating environment by cleaning the debris.正确答案A
