SS3B机车的通风保护是依靠（）继电器和1—4ZFJ制动风速继电器来执行保护的。
参考答案：1.2QFJ牵引风速
请完成图中的光路图。
The loading, unloading, transshipment and transit of inward and outward mail bags are （）Customs control and a covering way bill should be submitted to the Customs by the enterprise providing postal service.
A. subject to
B. upon
C. into
D. with
