在某些情况下，尤其是对于复杂的飞机，可能需要针对飞机及其系统的适当维修提供专门培训。
A.In some cases, for complex aircraft, special training should be conducted so that the aircraft and its systems can be maintained properly. B.Sometimes, especially for complex airplanes, it may be necessary to provide specific training in the proper maintenance of then airplane and its systems. C.Sometimes, for particularly complex airplanes, it is required to provide special training so as to perform proper maintenance of the aircraft and its systems.正确答案B
