为了在预处理空气连接单向阀在打开位置不工作时放行飞机，执行以下步骤。
A.For release with the ground preconditioned air connection single valve inoperative in the open position, do these steps. B.For dispatch with the ground preconditioned air connection check valve inoperative in the open position, do these steps. C.For release with the ground recondition ed air connection check valve inoperative in the open position ,do these steps.正确答案B
