They________extensiveandpossiblydangerousactualflighttraining.
B
句意：他们经历了大量的并且可能是危险的实际飞行训练。
Asactivitycarried________asonethinksfitinone’ssparetime,leisurehasseveralfunctions.
____yourinformation,wehavereceivedacrowdofenquiriesfrombuyersinotherdirections.()