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单选题
Before you do this procedure, engage the ramp service door safety connector pin.
A
Insert the pin of the apron service door security connector, then you can perform this procedure.
B
The ramp service door safety pin shouldn＇t be engaged until you start this procedure.
C
Firstly you should perform this procedure then you can engage the ramp service door safety connector pin.
答案解析
正确答案：A
